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Sample records for biofouling inhibiting coating

  1. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Schroll, Casper;

    2008-01-01

    Biofouling can cause many undesirable effects in industrial and medical settings. In this study, a new biofouling inhibiting Ag-Pd surface was designed to form an inhibiting effect by itself. This design was based on silver combined with nobler palladium, both with catalytic properties. Owing...... and biofouling inhibiting mechanism of these surfaces. In this study, the evidence is presented that the inhibiting effect can be caused by the electrochemical interactions and/or electric field between Pd and Ag/AgCl combined with an organic environment....

  2. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Møller, Per

    The undesired microbial and biofilm adhesions on the surfaces of food industrial facilities, water supply systems and etc. are so called as “biofouling”. Biofouling can cause many undesirable effects. Until now for solving biofouling, there are few non-toxic inhibiting treatments. In this study...

  3. Influence of polyelectrolyte multilayer coating on the degree and type of biofouling in freshwater environment.

    Science.gov (United States)

    Frueh, Johannes; Gai, Meiyu; Yang, Zhibo; He, Qiang

    2014-06-01

    Biofouling is one of the biggest problems of water-borne systems. Since not only marine but also freshwater-based structures are affected, the biofouling in this environment is studied. The focus of this study lies on the antifouling properties of novel coating materials like polyelectrolyte multilayers (PEM) compared with currently used silicon rubber (PDMS) based fouling release coatings. The following article contains the results of a systematical screening of the mechanical, surface charge and surface nano-heterogeneous properties of the investigated PEM and PDMS systems. The results show that negatively charged non crosslinked and crosslinked PEM coated PDMS can surpass current PDMS based fouling release coatings. The PEM films are not only able to reduce the biofouling, but are additionally able to control the type of settled bacteria (gram positive or negative). The negative terminated surfaces inhibit the settlement of gram positive bacteria, whereby the positive terminated surfaces inhibit the settlement of gram negative bacteria. PMID:24738394

  4. Biofouling Prevention of Ancient Brick Surfaces by TiO2-Based Nano-Coatings

    Directory of Open Access Journals (Sweden)

    Lorenzo Graziani

    2015-07-01

    Full Text Available Brick constitutes a significant part of the construction materials used in historic buildings around the world. This material was used in Architectural Heritage for structural scope, and even for building envelopes. Thus, components made of clay brick were subjected to weathering for a long time, and this causes their deterioration. One of the most important causes for deterioration is biodeterioration caused by algae and cyanobacteria. It compromises the aesthetical properties, and, at a later stage, the integrity of the elements. In fact, traditional products used for the remediation/prevention of biofouling do not ensure long-term protection, and they need re-application over time. The use of nanotechnology, especially the use of photocatalytic products for the prevention of organic contamination of building façades is increasing. In this study, TiO2-based photocatalytic nano-coatings were applied to ancient brick, and its efficiency towards biofouling was studied. A composed suspension of algae and cyanobacteria was sprinkled on the bricks’ surface for a duration of twelve weeks. Digital Image Analysis and colorimetric measurements were carried out to evaluate algal growth on specimens’ surfaces. Results show that photocatalytic nano-coating was able to inhibit biofouling on bricks’ surfaces. In addition, substrata (their porosity and roughness clearly influences the adhesion of algal cells.

  5. Mini-review: Inhibition of biofouling by marine microorganisms.

    Science.gov (United States)

    Dobretsov, Sergey; Abed, Raeid M M; Teplitski, Max

    2013-01-01

    Any natural or artificial substratum exposed to seawater is quickly fouled by marine microorganisms and later by macrofouling species. Microfouling organisms on the surface of a substratum form heterogenic biofilms, which are composed of multiple species of heterotrophic bacteria, cyanobacteria, diatoms, protozoa and fungi. Biofilms on artificial structures create serious problems for industries worldwide, with effects including an increase in drag force and metal corrosion as well as a reduction in heat transfer efficiency. Additionally, microorganisms produce chemical compounds that may induce or inhibit settlement and growth of other fouling organisms. Since the last review by the first author on inhibition of biofouling by marine microbes in 2006, significant progress has been made in the field. Several antimicrobial, antialgal and antilarval compounds have been isolated from heterotrophic marine bacteria, cyanobacteria and fungi. Some of these compounds have multiple bioactivities. Microorganisms are able to disrupt biofilms by inhibition of bacterial signalling and production of enzymes that degrade bacterial signals and polymers. Epibiotic microorganisms associated with marine algae and invertebrates have a high antifouling (AF) potential, which can be used to solve biofouling problems in industry. However, more information about the production of AF compounds by marine microorganisms in situ and their mechanisms of action needs to be obtained. This review focuses on the AF activity of marine heterotrophic bacteria, cyanobacteria and fungi and covers publications from 2006 up to the end of 2012.

  6. Revealing Amphiphilic Nanodornains of Anti-Biofouling Polymer Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amadei, CA; Yang, R; Chiesa, M; Gleason, KK; Santos, S

    2014-04-09

    Undesired bacterial adhesion and biofilm formation on wetted surfaces leads to significant economic and environmental costs in various industries. Amphiphilic coatings with molecular hydrophilic and hydrophobic patches can mitigate such biofouling effectively in an environmentally friendly manner. The coatings are synthesized by copolymerizing (Hydroxyethyl)methacrylate and perfluorodecylacrylate via initiated chemical vapor deposition (iCVD). In previous studies, the size of the patches was estimated to be similar to 1.4-1.75 nm by fitting protein adsorption data to a theoretical model. However, no direct observations of the molecular heterogeneity exist and therefore the origin of the fouling resistance of amphiphilic coatings remains unclear. Here, the amphiphilic nature is investigated by amplitude modulation atomic force microscopy (AM-AFM). High-resolution images obtained by penetrating and oscillating the AFM tip under the naturally present water layer with sub-nanometer amplitudes reveal, for the first time, the existence of amphiphilic nanodomains (1-2 nm(2)). Compositional heterogeneity at the nanoscale is further corroborated by a statistical analysis on the data obtained with dynamic AM-AFM force spectroscopy. Variations in the long range attractive forces, responsible for water affinity, are also identified. These nanoscopic results on the polymers wettability are also confirmed by contact angle measurements (i.e., static and dynamic). The unprecedented ability to visualize the amphiphilic nanodomains as well as sub-nanometer crystalline structures provides strong evidence for the existence of previously postulated nanostructures, and sheds light on the underlying antifouling mechanism of amphiphilic chemistry.

  7. Biofouling of Cr-Nickel Spray Coated Films on Steel Surfaces

    International Nuclear Information System (INIS)

    Nowadays, corrosion of metals brings us serious economic loss and it often reaches several percentage of GNP. Particularly the marine corrosion was serious and the counter measure was very hard to be established, since the number of factors is huge and complicated. One of the complicated factors in marine corrosion is biofouling. Biofouling was classified into two main categories, microfouling and macrofouling. The former is composed of biofilm formation mainly. Marine bacteria are attached to material surfaces, seeking for nutrition in oligotrophic environment and they excrete polysaccharide to form biofilm on metal surfaces. Then larger living matters are attached on the biofilms to develop biofouling on metal surfaces, which often lead loss and failures of metals in marine environments. From the viewpoint of corrosion protection and maintenance of marine structures, biofouling should be mitigated as much as possible. In this study, we applied spray coating to steels and investigated if chromium-nickel spray coating could mitigate the biofouling, being compared with the conventional aluminium-zinc spray coating in marine environments. The specimens used for this investigation are aluminium, zinc, aluminium-zinc, stacked chromium/nickel and those films were formed on carbon steel (JIS SS400). And the pores formed by spray coating were sealed by a commercial reagent for some specimens. All of those specimens were immersed into sea water located at Marina Kawage (854-3, Chisato, Tsu, Mie Prefecture) in Ise Bay for two weeks. The depth of the specimen was two meter from sea water surface and the distance was always kept constant, since they were suspended from the floating pier. The temperature in sea water changed from 10 to 15 degrees Celsius during the immersion test. The biofouling behavior was investigated by low vacuum SEM (Hitachi Miniscope TM1000) and X-ray fluorescent analysis. When the spray coated specimens with and without sealing agents were compared

  8. Impact of feed spacer and membrane modification by hydrophilic, bactericidal and biocidal coating on biofouling control

    KAUST Repository

    Araújo, Paula A.

    2012-06-01

    The influence of polydopamine- and polydopamine-. graft-poly(ethylene glycol)-coated feed spacers and membranes, copper-coated feed spacers, and commercially-available biostatic feed spacers on biofouling has been studied in membrane fouling simulators. Feed spacers and membranes applied in practical membrane filtration systems were used; biofouling development was monitored by feed channel pressure drop increase and biomass accumulation. Polydopamine and polydopamine-. g-PEG are hydrophilic surface modification agents expected to resist protein and bacterial adhesion, while copper feed spacer coatings and biocides infused in feed spacers are expected to restrict biological growth. Our studies showed that polydopamine and polydopamine-. g-PEG coatings on feed spacers and membranes, copper coatings on feed spacers, and a commercial biostatic feed spacer did not have a significant impact on feed channel pressure drop increase and biofilm accumulation as measured by ATP and TOC content. The studied spacer and membrane modifications were not effective for biofouling control; it is doubtful that feed spacer and membrane modification, in general, may be effective for biofouling control regardless of the type of applied coating. © 2012 Elsevier B.V.

  9. A bioinspired omniphobic surface coating on medical devices prevents thrombosis and biofouling.

    Science.gov (United States)

    Leslie, Daniel C; Waterhouse, Anna; Berthet, Julia B; Valentin, Thomas M; Watters, Alexander L; Jain, Abhishek; Kim, Philseok; Hatton, Benjamin D; Nedder, Arthur; Donovan, Kathryn; Super, Elana H; Howell, Caitlin; Johnson, Christopher P; Vu, Thy L; Bolgen, Dana E; Rifai, Sami; Hansen, Anne R; Aizenberg, Michael; Super, Michael; Aizenberg, Joanna; Ingber, Donald E

    2014-11-01

    Thrombosis and biofouling of extracorporeal circuits and indwelling medical devices cause significant morbidity and mortality worldwide. We apply a bioinspired, omniphobic coating to tubing and catheters and show that it completely repels blood and suppresses biofilm formation. The coating is a covalently tethered, flexible molecular layer of perfluorocarbon, which holds a thin liquid film of medical-grade perfluorocarbon on the surface. This coating prevents fibrin attachment, reduces platelet adhesion and activation, suppresses biofilm formation and is stable under blood flow in vitro. Surface-coated medical-grade tubing and catheters, assembled into arteriovenous shunts and implanted in pigs, remain patent for at least 8 h without anticoagulation. This surface-coating technology could reduce the use of anticoagulants in patients and help to prevent thrombotic occlusion and biofouling of medical devices.

  10. Biofouling control by quorum sensing inhibition and its dependence on membrane surface.

    Science.gov (United States)

    Kim, Mijin; Lee, Sangyoup; Park, Hee-Deung; Choi, Suing-Il; Hong, Seungkwan

    2012-01-01

    Biofouling control by quorum sensing (QS) inhibition and the influence of membrane surface characteristics on biofilm formation and QS inhibition were investigated. Pseudomonas putida isolated from the bio-fouled reverse osmosis (RO) membranes in a real plant was used. Acylase was chosen as a model QS inhibitor. Bacteria on the membrane coupons were quantified with the heterotrophic plate count method. Cell distribution was imaged by a confocal laser scanning microscope. Results showed that biofilm formation on the membrane was reduced by acylase as it inhibits the activity of N-acylhomoserine lactone (AHL) which is a signal molecule of QS. It was also shown that membrane surface characteristics were influential factors affecting bacterial adhesion, biofilm formation, and QS inhibition.

  11. A biomimetic nano hybrid coating based on the lotus effect and its anti-biofouling behaviors

    Science.gov (United States)

    Li, Jiang; Wang, Guoqing; Meng, Qinghua; Ding, Chunhua; Jiang, Hong; Fang, Yongzeng

    2014-10-01

    To develop an environmentally friendly anti-biofouling coating in virtue of bionics, a block copolymer containing fluorine (Coplm_F) of low surface energy was prepared by copolymerization. The Ag-loaded mesoporous silica (Ag@SBA) acting as a controlled-release antifoulant was prepared from the mesoporous silica (SBA-15). The nano hybrid coating (Ag@SBA/Coplm_F) composing of the Coplm_F and Ag@SBA was to biomimetically simulate the lotus microstructure. The concentration of fluorine element on surface was analyzed by the energy dispersive spectroscopy (EDS) and found rising to 1.45% after hybridation, which could be explained by the driving effect of SBA-15 via the hydrogen bond. This nanoscale morphology of the hybrid coating was measured and found highly semblable to the microstructure of the lotus surface. The contact angle was determined as 151° which confirmed the superhydrophobicity and lotus effect. The adhesion behaviors of Pseudomonas fluorescens, Diatoms, and Chlorella on the surface of the nano hybrid coating (Ag@SBA/Coplm_F) were studied and good effects of anti-biofouling were observed.

  12. Inhibition of biofouling by modification of forward osmosis membrane using quaternary ammonium cation.

    Science.gov (United States)

    Park, Kang-Hee; Yu, Sang-Hyun; Kim, Han-Shin; Park, Hee-Deung

    2015-01-01

    In the operation of the forward osmosis (FO) process, biofouling of the membrane is a potentially serious problem. Development of an FO membrane with antibacterial properties could contribute to a reduction in biofouling. In this study, quaternary ammonium cation (QAC), a widely used biocidal material, was conjugated with a silane coupling agent (3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride) and used to modify an FO membrane to confer antibacterial properties. Fourier transform infrared spectroscopy (FT-IR) demonstrated that the conjugated QAC was successfully immobilized on the FO membrane via covalent bonding. Bacterial viability on the QAC-modified membrane was confirmed via colony count method and visualized via bacterial viability assay. The QAC membrane decreased the viability of Escherichia coli to 62% and Staphylococcus aureus to 77% versus the control membrane. Inhibition of biofilm formation on the QAC modified membrane was confirmed via anti-biofilm tests using the drip-flow reactor and FO unit, resulting in 64% and 68% inhibition in the QAC-modified membrane against the control membrane, respectively. The results demonstrate the effectiveness of the modified membrane in reducing bacterial viability and inhibiting biofilm formation, indicating the potential of QAC-modified membranes to decrease operation costs incurred by biofouling.

  13. Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation

    NARCIS (Netherlands)

    Wibisono, Yusuf; Yandi, Wetra; Golabi, Mohsen; Nugraha, Roni; Cornelissen, Emile R.; Kemperman, Antoine J.B.; Ederth, Thomas; Nijmeijer, Kitty

    2015-01-01

    Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG10MA

  14. Silver coating effects on biofouling growth and morphology on heat transfer surfaces%换热表面镀银对微生物污垢的生长与形态的影响

    Institute of Scientific and Technical Information of China (English)

    杨倩鹏; 常思远; 史琳

    2013-01-01

    Silver ions provide bacteria sterilization effectively inhibit biofouling by bacteria.However,current research has mainly focused on the effects of silver ions in medical applications.For industrial applications like heat transfer surfaces,the effects of silver coatings on biofouling inhibition have rarely been reported.There are notable differences between silver ions in solution and silver coatings tihe the effectiveness dependent on the structure of the biofouling.There are also differences between planktonic bacteria in solution and in biofouling.This study focuses on the effects of silver on biofouling structures and growth rates to illustrate the mechanism and effectiveness of silver coatings.The results show the biofouling wet and dry weights both decreased more than 20% with a silver coating.The bottom biofouling layer became hollow and the bacteria cells in the biofouling within 100μm of the material surface showed decreased activity.%银离子溶液对悬浮细菌杀灭作用显著,对由细菌形成的微生物污垢也有明显抑制作用.当前,银离子溶液杀灭作用的研究主要集中在医学领域,对工业领域的换热器表面的镀银方式和微生物污垢形式涉及较少.镀银方式与银离子溶液作用机理有所差别,镀银方式与空间位置关系明显.微生物污垢形式,与菌液中悬浮细菌也有明显差异.该文从镀银对微生物污垢空间形态和重量曲线两方面出发,探讨了镀银抑垢的机理和效果.结果表明:镀银后污垢湿重量和干重量均下降20%以上.污垢底层空洞化,距离材料表面100 μm厚度以内污垢中的细胞活性下降.

  15. A nanomolecular approach to decrease adhesion of biofouling-producing bacteria to graphene-coated material

    OpenAIRE

    Parra, Carolina; Dorta, Fernando; Jimenez, Edra; Henríquez, Ricardo; Ramírez, Cristian; Rojas, Rodrigo; Villalobos, Patricio

    2015-01-01

    Background Biofouling, the colonization of artificial and natural surfaces by unwanted microorganisms, has an important economic impact on a wide range of industries. Low cost antifouling strategies are typically based on biocides which exhibit a negative environmental impact, affecting surrounding organisms related and not related to biofouling. Considering that the critical processes resulting in biofouling occur in the nanoscale/microscale dimensions, in this work we present a bionanotechn...

  16. Principles of biofouling protection in marine sponges: a model for the design of novel biomimetic and bio-inspired coatings in the marine environment?

    Science.gov (United States)

    Müller, Werner E G; Wang, Xiaohong; Proksch, Peter; Perry, Carole C; Osinga, Ronald; Gardères, Johan; Schröder, Heinz C

    2013-08-01

    The process of biofouling of marine structures and substrates, such as platforms or ship hulls, proceeds in multiple steps. Soon after the formation of an initial conditioning film, formed via the adsorption of organic particles to natural or man-made substrates, a population of different bacterial taxa associates under the formation of a biofilm. These microorganisms communicate through a complex quorum sensing network. Macro-foulers, e.g., barnacles, then settle and form a fouling layer on the marine surfaces, a process that globally has severe impacts both on the economy and on the environment. Since the ban of tributyltin, an efficient replacement of this antifouling compound by next-generation antifouling coatings that are environmentally more acceptable and also showing longer half-lives has not yet been developed. The sponges, as sessile filter-feeder animals, have evolved antifouling strategies to protect themselves against micro- and subsequent macro-biofouling processes. Experimental data are summarized and suggest that coating of the sponge surface with bio-silica contributes to the inhibition of the formation of a conditioning film. A direct adsorption of the surfaces by microorganisms can be impaired through poisoning the organisms with direct-acting secondary metabolites or toxic peptides. In addition, first, compounds from sponges have been identified that interfere with the anti-quorum sensing network. Sponge secondary metabolites acting selectively on diatom colonization have not yet been identified. Finally, it is outlined that direct-acting secondary metabolites inhibiting the growth of macro-fouling animals and those that poison the multidrug resistance pump are available. It is concluded that rational screening programs for inhibitors of the complex and dynamic problem of biofilm production, based on multidisciplinary studies and using sponges as a model, are required in the future. PMID:23525893

  17. Adsorption of alginate and albumin on aluminum coatings inhibits adhesion of Escherichia coli and enhances the anti-corrosion performances of the coatings

    Science.gov (United States)

    He, Xiaoyan; Liu, Yi; Huang, Jing; Chen, Xiuyong; Ren, Kun; Li, Hua

    2015-03-01

    Thermal-sprayed aluminum coatings have been extensively used as protective layers against corrosion for steel structures in the marine environment. The corrosion usually deteriorates from marine biofouling, yet the mechanism of accelerated corrosion of the coatings remains elusive. As the first stage participating in biofouling process, adsorption of molecules plays critical roles in mediating formation of biofilm. Here, we report at molecular level the adsorption behaviors of albumin and marine polysaccharide on arc-sprayed aluminum coatings and their influence on adhesion of Escherichia coli. The adsorption of alginate and albumin was characterized by infrared spectra analyses and atomic force microscopic observation. The adsorption inhibits effectively adhesion of the bacteria. Further investigation indicates that alginate/albumin altered the hydrophilicity/hydrophobicity of the coatings instead of impacting the survival of the bacteria to decline their adhesion. The conditioning layer composed of the molecules enhances anti-corrosion performances of the coatings.

  18. Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: a novel platform for eco-friendly biofouling mitigation.

    Science.gov (United States)

    Wibisono, Yusuf; Yandi, Wetra; Golabi, Mohsen; Nugraha, Roni; Cornelissen, Emile R; Kemperman, Antoine J B; Ederth, Thomas; Nijmeijer, Kitty

    2015-03-15

    Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG10MA), cationic (polyDMAEMA) and anionic (polySPMA) hydrogels have been successfully grafted onto polypropylene (PP) feed spacers via plasma-mediated UV-polymerization. These coatings maintained their chemical stability after 7 days incubation in neutral (pH 7), acidic (pH 5) and basic (pH 9) environments. Anti-biofouling properties of these coatings were evaluated by Escherichia coli attachment assay and nanofiltration experiments at a TMP of 600 kPag using tap water with additional nutrients as feed and by using optical coherence tomography. Especially the anionic polySPMA-coated PP feed spacer shows reduced attachment of E. coli and biofouling in the spacer-filled narrow channels resulting in delayed biofilm growth. Employing this highly hydrophilic coating during removal of biofouling by two-phase flow cleaning also showed enhanced cleaning efficiency, feed channel pressure drop and flux recoveries. The strong hydrophilic nature and the presence of negative charge on polySPMA are most probably responsible for the improved antifouling behavior. A combination of polySPMA-coated PP feed spacers and two-phase flow cleaning therefore is promising and an environmentally friendly approach to control biofouling in NF/RO systems employing spiral-wound membrane modules.

  19. Analysis of micromixers and biocidal coatings on water-treatment membranes to minimize biofouling.

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Stephen W.; James, Darryl L. (Texas Tech University, Lubbock, TX); Hibbs, Michael R.; Jones, Howland D. T.; Hart, William Eugene; Khalsa, Siri Sahib; Altman, Susan Jeanne; Clem, Paul Gilbert; Elimelech, Menachem (Yale University, New Haven, CT); Cornelius, Christopher James; Sanchez, Andres L. (LMATA Government Services LLC, Albuquerque, NM); Noek, Rachael M.; Ho, Clifford Kuofei; Kang, Seokatae (Yale University, New Haven, CT); Sun, Amy Cha-Tien; Adout, Atar (Yale University, New Haven, CT); McGrath, Lucas K. (LMATA Government Services LLC, Albuquerque, NM); Cappelle, Malynda A.; Cook, Adam W.

    2009-12-01

    Biofouling, the unwanted growth of biofilms on a surface, of water-treatment membranes negatively impacts in desalination and water treatment. With biofouling there is a decrease in permeate production, degradation of permeate water quality, and an increase in energy expenditure due to increased cross-flow pressure needed. To date, a universal successful and cost-effect method for controlling biofouling has not been implemented. The overall goal of the work described in this report was to use high-performance computing to direct polymer, material, and biological research to create the next generation of water-treatment membranes. Both physical (micromixers - UV-curable epoxy traces printed on the surface of a water-treatment membrane that promote chaotic mixing) and chemical (quaternary ammonium groups) modifications of the membranes for the purpose of increasing resistance to biofouling were evaluated. Creation of low-cost, efficient water-treatment membranes helps assure the availability of fresh water for human use, a growing need in both the U. S. and the world.

  20. Adsorption of alginate and albumin on aluminum coatings inhibits adhesion of Escherichia coli and enhances the anti-corrosion performances of the coatings

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Adsorption behaviors of alginate and albumin on Al coatings were investigated at molecular level. • The adsorption inhibits effectively the colonization of Escherichia coli bacteria. • The adsorption alters the wettability of the Al coatings. • The conditioning layer enhances anti-corrosion performances of the Al coatings. - Abstract: Thermal-sprayed aluminum coatings have been extensively used as protective layers against corrosion for steel structures in the marine environment. The corrosion usually deteriorates from marine biofouling, yet the mechanism of accelerated corrosion of the coatings remains elusive. As the first stage participating in biofouling process, adsorption of molecules plays critical roles in mediating formation of biofilm. Here, we report at molecular level the adsorption behaviors of albumin and marine polysaccharide on arc-sprayed aluminum coatings and their influence on adhesion of Escherichia coli. The adsorption of alginate and albumin was characterized by infrared spectra analyses and atomic force microscopic observation. The adsorption inhibits effectively adhesion of the bacteria. Further investigation indicates that alginate/albumin altered the hydrophilicity/hydrophobicity of the coatings instead of impacting the survival of the bacteria to decline their adhesion. The conditioning layer composed of the molecules enhances anti-corrosion performances of the coatings

  1. Adsorption of alginate and albumin on aluminum coatings inhibits adhesion of Escherichia coli and enhances the anti-corrosion performances of the coatings

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiaoyan; Liu, Yi; Huang, Jing; Chen, Xiuyong; Ren, Kun; Li, Hua, E-mail: lihua@nimte.ac.cn

    2015-03-30

    Graphical abstract: - Highlights: • Adsorption behaviors of alginate and albumin on Al coatings were investigated at molecular level. • The adsorption inhibits effectively the colonization of Escherichia coli bacteria. • The adsorption alters the wettability of the Al coatings. • The conditioning layer enhances anti-corrosion performances of the Al coatings. - Abstract: Thermal-sprayed aluminum coatings have been extensively used as protective layers against corrosion for steel structures in the marine environment. The corrosion usually deteriorates from marine biofouling, yet the mechanism of accelerated corrosion of the coatings remains elusive. As the first stage participating in biofouling process, adsorption of molecules plays critical roles in mediating formation of biofilm. Here, we report at molecular level the adsorption behaviors of albumin and marine polysaccharide on arc-sprayed aluminum coatings and their influence on adhesion of Escherichia coli. The adsorption of alginate and albumin was characterized by infrared spectra analyses and atomic force microscopic observation. The adsorption inhibits effectively adhesion of the bacteria. Further investigation indicates that alginate/albumin altered the hydrophilicity/hydrophobicity of the coatings instead of impacting the survival of the bacteria to decline their adhesion. The conditioning layer composed of the molecules enhances anti-corrosion performances of the coatings.

  2. 2(5H-Furanone: a prospective strategy for biofouling-control in membrane biofilm bacteria by quorum sensing inhibition

    Directory of Open Access Journals (Sweden)

    Kannan Ponnusamy

    2010-03-01

    Full Text Available Biofouling of membranes demands costly periodic cleaning and membrane replacement. A sustainable and environmentally friendly solution for maintenance is not available and would be of great interest for many purposes including economical. As complex biofilm formation by environmental strains is the major cause of biofouling and biofilm formation in most cases are controlled by N-Acylhomoserine lactone (AHLmediated Quorum Sensing (QS. An effort was made to understand the appropriateness of 2(5H-furanone, to use against biofouling of membranes. QS inhibition activity by 2(5H-furanone was studied using bioindicator strains and known AHLs of different acyl chain lengths. The biofilm inhibition was studied by growth analysis on polystyrene plate of Aeromonas hyrdrophila, an environmental biofilm strain isolated from a bio-fouled reverse osmosis (RO membrane. Results showed a QS inhibition activity against a wide range of AHLs and also biofilm formation by 2(5H-furanone, which is believed to act as a potential quorum inhibition agent in a bacterial biofilm community.

  3. Inhibition of Cariogenic Plaque Formation on Root Surface with Polydopamine-Induced-Polyethylene Glycol Coating

    Directory of Open Access Journals (Sweden)

    May Lei Mei

    2016-05-01

    Full Text Available Root caries prevention has been a challenge for clinicians due to its special anatomical location, which favors the accumulation of dental plaque. Researchers are looking for anti-biofouling material to inhibit bacterial growth on exposed root surfaces. This study aimed to develop polydopamine-induced-polyethylene glycol (PEG and to study its anti-biofouling effect against a multi-species cariogenic biofilm on the root dentine surface. Hydroxyapatite disks and human dentine blocks were divided into four groups for experiments. They received polydopamine-induced-PEG, PEG, polydopamine, or water application. Contact angle, quartz crystal microbalance, and Fourier transform infrared spectroscopy were used to study the wetting property, surface affinity, and an infrared spectrum; the results indicated that PEG was induced by polydopamine onto a hydroxyapatite disk. Salivary mucin absorption on hydroxyapatite disks with polydopamine-induced-PEG was confirmed using spectrophotometry. The growth of a multi-species cariogenic biofilm on dentine blocks with polydopamine-induced-PEG was assessed and monitored by colony-forming units, confocal laser scanning microscopy, and scanning electron microscopy. The results showed that dentine with polydopamine-induced-PEG had fewer bacteria than other groups. In conclusion, a novel polydopamine-induced-PEG coating was developed. Its anti-biofouling effect inhibited salivary mucin absorption and cariogenic biofilm formation on dentine surface and thus may be used for the prevention of root dentine caries.

  4. Polysulfone and polyacrylate-based zwitterionic coatings for the prevention and easy removal of marine biofouling.

    Science.gov (United States)

    Hibbs, Michael R; Hernandez-Sanchez, Bernadette A; Daniels, Justin; Stafslien, Shane J

    2015-01-01

    A series of polysulfone and polyacrylate-based zwitterionic coatings were prepared on epoxy-primed aluminum substrata and characterized for their antifouling (AF) and fouling-release (FR) properties towards marine bacteria, microalgae and barnacles. The zwitterionic polymer coatings provided minimal resistance against bacterial biofilm retention and microalgal cell attachment, but facilitated good removal of attached microbial biomass by exposure to water-jet apparatus generated hydrodynamic shearing forces. Increasing the ion content of the coatings improved the AF properties, but required a stronger adhesive bond to the epoxy-primed aluminum substratum to prevent coating swelling and dissolution. Grafted poly(sulfobetaine) (gpSBMA), the most promising zwitterionic coating identified from microfouling evaluations, enabled the removal of four out of five barnacles reattached to its surface without incurring damage to their baseplates. This significant result indicated that gpSBMA relied predominately on its surface chemistry for its FR properties since it was very thin (~1-2 µm) relative to commercial coating standards (>200 µm).

  5. Modern approaches to marine antifouling coatings

    OpenAIRE

    Chambers, Lily D.; Stokes, Keith R.; Walsh, Frank.C.; Robert J.K. Wood

    2006-01-01

    Marine structures such as platforms, jetties and ship hulls are subject to diverse and severe biofouling. Methods for inhibiting both organic and inorganic growth on wetted substrates are varied but most antifouling systems take the form of protective coatings. Biofouling can negatively affect the hydrodynamics of a hull by increasing the required propulsive power and the fuel consumption. This paper reviews the development of antifouling coatings for the prevention of marine biological fouli...

  6. Biofouling: lessons from nature.

    Science.gov (United States)

    Bixler, Gregory D; Bhushan, Bharat

    2012-05-28

    Biofouling is generally undesirable for many applications. An overview of the medical, marine and industrial fields susceptible to fouling is presented. Two types of fouling include biofouling from organism colonization and inorganic fouling from non-living particles. Nature offers many solutions to control fouling through various physical and chemical control mechanisms. Examples include low drag, low adhesion, wettability (water repellency and attraction), microtexture, grooming, sloughing, various miscellaneous behaviours and chemical secretions. A survey of nature's flora and fauna was taken in order to discover new antifouling methods that could be mimicked for engineering applications. Antifouling methods currently employed, ranging from coatings to cleaning techniques, are described. New antifouling methods will presumably incorporate a combination of physical and chemical controls.

  7. Effects of biofouling development on drag forces of hull coatings for ocean-going ships: a review

    DEFF Research Database (Denmark)

    Lindholdt, Asger; Dam-Johansen, Kim; Olsen, S. M.;

    2015-01-01

    This review presents a systematic overview of the literature and describes the experimental methods used to quantify the drag of hull coatings. It also summarizes the findings of hull coating's drag performance and identifies the main parameters impacting it. The advantages and disadvantages...... of the reported methods listed in this review provide an assessment of the most efficient methods to quantify the drag performance of hull coatings. This review determines that drag performance of hull coating technology varies depending on whether the coating condition is newly applied, after dynamic or static...

  8. Single-Step Assembly of Multifunctional Poly(tannic acid)-Graphene Oxide Coating To Reduce Biofouling of Forward Osmosis Membranes.

    Science.gov (United States)

    Hegab, Hanaa M; ElMekawy, Ahmed; Barclay, Thomas G; Michelmore, Andrew; Zou, Linda; Saint, Christopher P; Ginic-Markovic, Milena

    2016-07-13

    Graphene oxide (GO) nanosheets have antibacterial properties that have been exploited as a biocidal agent used on desalination membrane surfaces in recent research. Nonetheless, improved strategies for efficient and stable attachment of GO nanosheets onto the membrane surface are still required for this idea to be commercially viable. To address this challenge, we adopted a novel, single-step surface modification approach using tannic acid cross-linked with polyethylene imine as a versatile platform to immobilize GO nanosheets to the surface of polyamide thin film composite forward osmosis (FO) membranes. An experimental design based on Taguchi's statistical method was applied to optimize the FO processing conditions in terms of water and reverse solute fluxes. Modified membranes were analyzed using water contact angle, adenosine triphosphate bioluminescence, total organic carbon, Fourier transform infrared spectroscopy, ζ potential, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy. These results show that membranes were modified with a nanoscale (<10 nm), smooth, hydrophilic coating that, compared to pristine membranes, improved filtration and significantly mitigated biofouling by 33% due to its extraordinary, synergistic antibacterial properties (99.9%). PMID:27294568

  9. Biofouling and barnacle adhesion data for fouling-release coatings subjected to static immersion at seven marine sites

    Digital Repository Service at National Institute of Oceanography (India)

    Swain, G.; Anil, A.C.; Baier, R.E.; Chia, F.-S.; Conte, E.; Cook, A.; Hadfield, M.; Haslbeck, E.; Holm, E.; Kavanagh, C.; Kohrs, D.; Kovach, B.; Lee, C.; Mazzella, L.; Meyer, A.E.; Qian, P.-Y.; Sawant, S.S.; Schultz, M.; Sigurdsson, J.; Smith, C.; Soo, L.; Terlizzi, A.; Wagh, A.; Zimmerman, R.; Zupo, V.

    and an epoxy control at seven static immersion sites located in California, Florida, Hawaii, Hong Kong, India, Italy and Singapore. The study found that whilst the relative performance of the coatings was similar at each site, there were statistically...

  10. Influence of elastomeric seal plate surface chemistry on interface integrity in biofouling-prone systems: Evaluation of a hydrophobic "easy-release" silicone-epoxy coating for maintaining water seal integrity of a sliding neoprene/steel interface

    Science.gov (United States)

    Andolina, Vincent L.

    The scientific hypothesis of this work is that modulation of the properties of hard materials to exhibit abrasion-reducing and low-energy surfaces will extend the functional lifetimes of elastomeric seals pressed against them in abrasive underwater systems. The initial motivation of this work was to correct a problem noted in the leaking of seals at major hydropower generating facilities subject to fouling by abrasive zebra mussel shells and extensive corrosion. Similar biofouling-influenced problems can develop at seals in medical devices and appliances from regulators in anesthetic machines and SCUBA diving oxygen supply units to autoclave door seals, injection syringe gaskets, medical pumps, drug delivery components, and feeding devices, as well as in food handling equipment like pasteurizers and transfer lines. Maritime and many other heavy industrial seal interfaces could also benefit from this coating system. Little prior work has been done to elucidate the relationship of seal plate surface properties to the friction and wear of elastomeric seals during sliding contacts of these articulating materials, or to examine the secondary influence of mineralized debris within the contacting interfaces. This investigation utilized the seal materials relevant to the hydropower application---neoprene elastomer against carbon steel---with and without the application of a silicone-epoxy coating (WearlonRTM 2020.98) selected for its wear-resistance, hydrophobicity, and "easy-release" capabilities against biological fouling debris present in actual field use. Analytical techniques applied to these materials before and after wear-producing processes included comprehensive Contact Angle measurements for Critical Surface Tension (CA-CST) determination, Scanning Electron Microscopic inspections, together with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-Ray Fluorescence (XRF) measurements for determination of surface texture and inorganic composition, Multiple

  11. The potential of nano-structured silicon oxide type coatings deposited by PACVD for control of aquatic biofouling

    NARCIS (Netherlands)

    Akesso, L.; Pettitt, M.E.; Callow, J.A.; Callow, M.E.; Stallard, J.; Teer, D.; Liu, C.; Wang, S.; Zhao, Q.; D'Souza, F.; Willemsen, P.R.; Donnelly, G.T.; Donik, C.; Kocijan, A.; Jenko, M.; Jones, L.A.; Guinaldo, P.C.

    2009-01-01

    SiOx-like coatings were deposited on glass slides from a hexamethylsiloxane precursor by plasma-assisted CVD (PACVD). Surface energies (23.1-45.7 mJ m-1) were correlated with the degree of surface oxidation and hydrocarbon contents. Tapping mode AFM revealed a range of surface topologies with Ra val

  12. Influence of surface conditioning and morphology on biofouling

    OpenAIRE

    Thome, Isabel

    2013-01-01

    Biofouling, the undesired colonization of surfaces, is a major problem for marine-related industries. To prevent unwanted effects caused by biofouling, suitable non-toxic coatings for the marine environment are required. Conditioning, i.e. the adsorption of proteins and macromolecules influences, as surface chemistry and morphology do, the settlement of fouling oragnisms. Investigating the temporal dynamics of conditioning film formation on functionalized self assembled mono...

  13. Influence of elastomeric seal plate surface chemistry on interface integrity in biofouling-prone systems: Evaluation of a hydrophobic "easy-release" silicone-epoxy coating for maintaining water seal integrity of a sliding neoprene/steel interface

    Science.gov (United States)

    Andolina, Vincent L.

    The scientific hypothesis of this work is that modulation of the properties of hard materials to exhibit abrasion-reducing and low-energy surfaces will extend the functional lifetimes of elastomeric seals pressed against them in abrasive underwater systems. The initial motivation of this work was to correct a problem noted in the leaking of seals at major hydropower generating facilities subject to fouling by abrasive zebra mussel shells and extensive corrosion. Similar biofouling-influenced problems can develop at seals in medical devices and appliances from regulators in anesthetic machines and SCUBA diving oxygen supply units to autoclave door seals, injection syringe gaskets, medical pumps, drug delivery components, and feeding devices, as well as in food handling equipment like pasteurizers and transfer lines. Maritime and many other heavy industrial seal interfaces could also benefit from this coating system. Little prior work has been done to elucidate the relationship of seal plate surface properties to the friction and wear of elastomeric seals during sliding contacts of these articulating materials, or to examine the secondary influence of mineralized debris within the contacting interfaces. This investigation utilized the seal materials relevant to the hydropower application---neoprene elastomer against carbon steel---with and without the application of a silicone-epoxy coating (WearlonRTM 2020.98) selected for its wear-resistance, hydrophobicity, and "easy-release" capabilities against biological fouling debris present in actual field use. Analytical techniques applied to these materials before and after wear-producing processes included comprehensive Contact Angle measurements for Critical Surface Tension (CA-CST) determination, Scanning Electron Microscopic inspections, together with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-Ray Fluorescence (XRF) measurements for determination of surface texture and inorganic composition, Multiple

  14. Quorum quenching mediated approaches for control of membrane biofouling.

    Science.gov (United States)

    Lade, Harshad; Paul, Diby; Kweon, Ji Hyang

    2014-01-01

    Membrane biofouling is widely acknowledged as the most frequent adverse event in wastewater treatment systems resulting in significant loss of treatment efficiency and economy. Different strategies including physical cleaning and use of antimicrobial chemicals or antibiotics have been tried for reducing membrane biofouling. Such traditional practices are aimed to eradicate biofilms or kill the bacteria involved, but the greater efficacy in membrane performance would be achieved by inhibiting biofouling without interfering with bacterial growth. As a result, the search for environmental friendly non-antibiotic antifouling strategies has received much greater attention among scientific community. The use of quorum quenching natural compounds and enzymes will be a potential approach for control of membrane biofouling. This approach has previously proven useful in diseases and membrane biofouling control by triggering the expression of desired phenotypes. In view of this, the present review is provided to give the updated information on quorum quenching compounds and elucidate the significance of quorum sensing inhibition in control of membrane biofouling.

  15. Nanoscale Plasma Coating Inhibits Formation of Staphylococcus aureus Biofilm.

    Science.gov (United States)

    Xu, Yuanxi; Jones, John E; Yu, Haiqing; Yu, Qingsong; Christensen, Gordon D; Chen, Meng; Sun, Hongmin

    2015-12-01

    Staphylococcus aureus commonly infects medical implants or devices, with devastating consequences for the patient. The infection begins with bacterial attachment to the device, followed by bacterial multiplication over the surface of the device, generating an adherent sheet of bacteria known as a biofilm. Biofilms resist antimicrobial therapy and promote persistent infection, making management difficult to futile. Infections might be prevented by engineering the surface of the device to discourage bacterial attachment and multiplication; however, progress in this area has been limited. We have developed a novel nanoscale plasma coating technology to inhibit the formation of Staphylococcus aureus biofilms. We used monomeric trimethylsilane (TMS) and oxygen to coat the surfaces of silicone rubber, a material often used in the fabrication of implantable medical devices. By quantitative and qualitative analysis, the TMS/O2 coating significantly decreased the in vitro formation of S. aureus biofilms; it also significantly decreased in vivo biofilm formation in a mouse model of foreign-body infection. Further analysis demonstrated TMS/O2 coating significantly changed the protein adsorption, which could lead to reduced bacterial adhesion and biofilm formation. These results suggest that TMS/O2 coating can be used to effectively prevent medical implant-related infections.

  16. Short-term adhesion and long-term biofouling testing of polydopamine and poly(ethylene glycol) surface modifications of membranes and feed spacers for biofouling control

    KAUST Repository

    Miller, Daniel J.

    2012-08-01

    Ultrafiltration, nanofiltration membranes and feed spacers were hydrophilized with polydopamine and polydopamine- g-poly(ethylene glycol) surface coatings. The fouling propensity of modified and unmodified membranes was evaluated by short-term batch protein and bacterial adhesion tests. The fouling propensity of modified and unmodified membranes and spacers was evaluated by continuous biofouling experiments in a membrane fouling simulator. The goals of the study were: 1) to determine the effectiveness of polydopamine and polydopamine- g-poly(ethylene glycol) membrane coatings for biofouling control and 2) to compare techniques commonly used in assessment of membrane biofouling propensity with biofouling experiments under practical conditions. Short-term adhesion tests were carried out under static, no-flow conditions for 1 h using bovine serum albumin, a common model globular protein, and Pseudomonas aeruginosa, a common model Gram-negative bacterium. Biofouling tests were performed in a membrane fouling simulator (MFS) for several days under flow conditions similar to those encountered in industrial modules with the autochthonous drinking water population and acetate dosage as organic substrate. Polydopamine- and polydopamine- g-poly(ethylene glycol)-modified membranes showed significantly reduced adhesion of bovine serum albumin and P. aeruginosa in the short-term adhesion tests, but no reduction of biofouling was observed during longer biofouling experiments with modified membranes and spacers. These results demonstrate that short-term batch adhesion experiments using model proteins or bacteria under static conditions are not indicative of biofouling, while continuous biofouling experiments showed that membrane surface modification by polydopamine and polydopamine- g-poly(ethylene glycol) is not effective for biofouling control. © 2012 Elsevier Ltd.

  17. Inhibition of Sulfide Mineral Oxidation by Surface Coating Agents: Batch

    Science.gov (United States)

    Choi, J.; Ji, M. K.; Yun, H. S.; Park, Y. T.; Gee, E. D.; Lee, W. R.; Jeon, B.-H.

    2012-04-01

    Mining activities and mineral industries have impacted on rapid oxidation of sulfide minerals such as pyrite (FeS2) which leads to Acid Mine Drainage (AMD) formation. Some of the abandoned mines discharge polluted water without proper environmental remediation treatments, largely because of financial constraints in treating AMD. Magnitude of the problem is considerable, especially in countries with a long history of mining. As metal sulfides become oxidized during mining activities, the aqueous environment becomes acid and rich in many metals, including iron, lead, mercury, arsenic and many others. The toxic heavy metals are responsible for the environmental deterioration of stream, groundwater and soils. Several strategies to remediate AMD contaminated sites have been proposed. Among the source inhibition and prevention technologies, microencapsulation (coating) has been considered as a promising technology. The encapsulation is based on inhibition of O2 diffusion by surface coating agent and is expected to control the oxidation of pyrite for a long time. Potential of several surface coating agents for preventing oxidation of metal sulfide minerals from both Young-Dong coal mine and Il-Gwang gold mine were examined by conducting batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH2PO4, MgO and KMnO4 as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H2O2 or NaClO). Batch experiments with Young-Dong coal mine samples showed least SO42- production in presence of KMnO4 (16% sulfate production compared to no surface coating agents) or cement (4%) within 8 days. In the case of Il-Gwang mine samples, least SO42- production was observed in presence of KH2PO4 (8%) or cement (2%) within 8 days. Field-scale pilot tests at Il-Gwang site also showed that addition of KH2PO4 decreased sulfate production from 200 to

  18. Biofouling ecology as a means to better understand membrane biofouling.

    Science.gov (United States)

    Vanysacker, Louise; Boerjan, Bart; Declerck, Priscilla; Vankelecom, Ivo F J

    2014-10-01

    Despite more than a decade of worldwide research on membrane fouling in membrane bioreactors, many questions remain to be answered. Biofouling, which is referred to as the unwanted deposition and growth of biofilms, remains the main problem. Due to its complexity, most of the existing anti-biofouling strategies are not completely successful. To unravel this complexity and finally to developed well-adapted control strategies, a microbial-based description of the biofouling development is needed. Therefore, in this review, the biofouling formation will be described as a typical biofilm formation in five steps including the formation of a conditioning film, the bacterial attachment, the production of extracellular polymeric substances, the biofilm maturation, and the bacterial detachment. Moreover, important processes such as hydrodynamics and bacterial communication or quorum sensing will be taken into account. It is finally discussed whether biofouling formation is an active or inactive biofilm process together with suggestion for further research.

  19. Bacterial growth on chitosan-coated polypropylene textile.

    Science.gov (United States)

    Erben, D; Hola, V; Jaros, J; Rahel, J

    2012-01-01

    Biofouling is a problem common in all systems where microorganisms and aqueous environment meet. Prevention of biofouling is therefore important in many industrial processes. The aim of this study was to develop a method to evaluate the ability of material coating to inhibit biofilm formation. Chitosan-coated polypropylene nonwoven textile was prepared using dielectric barrier discharge plasma activation. Resistance of the textile to biofouling was then tested. First, the textile was submerged into a growth medium inoculated with green fluorescein protein labelled Pseudomonas aeruginosa. After overnight incubation at 33°C, the textile was observed using confocal laser scanning microscopy for bacterial enumeration and biofilm structure characterisation. In the second stage, the textile was used as a filter medium for prefiltered river water, and the pressure development on the in-flow side was measured to quantify the overall level of biofouling. In both cases, nontreated textile samples were used as a control. The results indicate that the chitosan coating exhibits antibacterial properties. The developed method is applicable for the evaluation of the ability to inhibit biofilm formation. PMID:23724330

  20. Single-Step Assembly of Multifunctional Poly(tannic acid)-Graphene Oxide Coating To Reduce Biofouling of Forward Osmosis Membranes.

    Science.gov (United States)

    Hegab, Hanaa M; ElMekawy, Ahmed; Barclay, Thomas G; Michelmore, Andrew; Zou, Linda; Saint, Christopher P; Ginic-Markovic, Milena

    2016-07-13

    Graphene oxide (GO) nanosheets have antibacterial properties that have been exploited as a biocidal agent used on desalination membrane surfaces in recent research. Nonetheless, improved strategies for efficient and stable attachment of GO nanosheets onto the membrane surface are still required for this idea to be commercially viable. To address this challenge, we adopted a novel, single-step surface modification approach using tannic acid cross-linked with polyethylene imine as a versatile platform to immobilize GO nanosheets to the surface of polyamide thin film composite forward osmosis (FO) membranes. An experimental design based on Taguchi's statistical method was applied to optimize the FO processing conditions in terms of water and reverse solute fluxes. Modified membranes were analyzed using water contact angle, adenosine triphosphate bioluminescence, total organic carbon, Fourier transform infrared spectroscopy, ζ potential, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy. These results show that membranes were modified with a nanoscale (biofouling by 33% due to its extraordinary, synergistic antibacterial properties (99.9%).

  1. Biofouling Control in Cooling Water

    Directory of Open Access Journals (Sweden)

    T. Reg Bott

    2009-01-01

    Full Text Available An important aspect of environmental engineering is the control of greenhouse gas emissions. Fossil fuel-fired power stations, for instance, represent a substantial contribution to this problem. Unless suitable steps are taken the accumulation of microbial deposits (biofouling on the cooling water side of the steam condensers can reduce their efficiency and in consequence, the overall efficiency of power production, with an attendant increase in fuel consumption and hence CO2 production. Biofouling control, therefore, is extremely important and can be exercised by chemical or physical techniques or a combination of both. The paper gives some examples of the effectiveness of different approaches to biofouling control.

  2. ANTI-BIOFOULING BY DEGRADATION OF POLYMERS

    Institute of Scientific and Technical Information of China (English)

    Chun-feng Ma; Hong-jun Yang; Guang-zhao Zhang

    2012-01-01

    Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate)(PEOC) macromonomer (PEOCA) were synthesized,and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D).It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains.Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.

  3. The potential of standard and modified feed spacers for biofouling control

    KAUST Repository

    Araújo, Paula A.

    2012-06-01

    The impact of feed spacers on initial feed channel pressure (FCP) drop, FCP increase and biomass accumulation has been studied in membrane fouling simulators using feed spacers applied in commercially available nanofiltration and reverse osmosis spiral wound membrane modules. All spacers had a similar geometry.Our studies showed that biofouling was not prevented by (i) variation of spacer thickness, (ii) feed spacer orientation, (iii) feed spacer coating with silver, copper or gold and (iv) using a biostatic feed spacer. At constant feed flow, a lower FCP and FCP increase were observed for a thicker feed spacer. At constant linear flow velocity, roughly the same FCP development and biomass accumulation were found irrespective of the feed spacer thickness: hydrodynamics and substrate load were more important for development and impact of biofouling than the thickness of currently applied spacers. Use of biostatic and metal coated spacers were not effective for biofouling control. The same small reduction of biofouling rate was observed with copper and silver coated spacers as well as uncoated 45° rotated spacers.The studied modified spacers were not effective for biofouling prevention and control. The impact of biofouling on FCP increase was reduced significantly by a lower linear flow velocity, while spacer orientation and spacer thickness in membrane modules had a smaller but still significant effect. © 2012 Elsevier B.V.

  4. Aluminum phosphate coatings

    Science.gov (United States)

    Sambasivan, Sankar; Steiner, Kimberly A.; Rangan, Krishnaswamy K.

    2007-12-25

    Aluminophosphate compounds and compositions as can be used for substrate or composite films and coating to provide or enhance, without limitation, planarization, anti-biofouling and/or anti-microbial properties.

  5. The role of "inert" surface chemistry in marine biofouling prevention.

    Science.gov (United States)

    Rosenhahn, Axel; Schilp, Sören; Kreuzer, Hans Jürgen; Grunze, Michael

    2010-05-01

    The settlement and colonization of marine organisms on submerged man-made surfaces is a major economic problem for many marine industries. The most apparent detrimental effects of biofouling are increased fuel consumption of ships, clogging of membranes and heat exchangers, disabled underwater sensors, and growth of biofoulers in aquaculture systems. The presently common-but environmentally very problematic-way to deal with marine biofouling is to incorporate biocides, which use biocidal products in the surface coatings to kill the colonizing organisms, into the surface coatings. Since the implementation of the International Maritime Organization Treaty on biocides in 2008, the use of tributyltin (TBT) is restricted and thus environmentally benign but effective surface coatings are required. In this short review, we summarize the different strategies which are pursued in academia and industry to better understand the mechanisms of biofouling and to develop strategies which can be used for industrial products. Our focus will be on chemically "inert" model surface coatings, in particular oligo- and poly(ethylene glycol) (OEG and PEG) functionalized surface films. The reasons for choosing this class of chemistry as an example are three-fold: Firstly, experiments on spore settlement on OEG and PEG coatings help to understand the mechanism of non-fouling of highly hydrated interfaces; secondly, these studies defy the common assumption that surface hydrophilicity-as measured by water contact angles-is an unambiguous and predictive tool to determine the fouling behavior on the surface; and thirdly, choosing this system is a good example for "interfacial systems chemistry": it connects the behavior of unicellular marine organisms with the antifouling properties of a hydrated surface coating with structural and electronic properties as derived from ab initio quantum mechanical calculations using the electronic wave functions of oxygen, hydrogen, and carbon. This short

  6. Superhydrophobic resistance to dynamic freshwater biofouling inception.

    Science.gov (United States)

    Krishnan, K Ghokulla; Malm, Peter; Loth, Eric

    2015-01-01

    Superhydrophobic nanotextured surfaces have gained increased usage in various applications due to their non-wetting and self-cleaning abilities. The aim of this study was to investigate nanotextured surfaces with respect to their resistance to the inception of freshwater biofouling at transitional flow conditions. Several coatings were tested including industry standard polyurethane (PUR), polytetrafluoroethylene (PTFE), capstone mixed polyurethane (PUR + CAP) and nanocomposite infused polyurethane (PUR + NC). Each surface was exposed to freshwater conditions in a lake at 4 m s(-1) for a duration of 45 min. The polyurethane exhibited the greatest fouling elements, in terms of both height and number of elements, with the superhydrophobic nanocomposite based polyurethane (PUR + NC) showing very little to no fouling. A correlation between the surface characteristics and the degree of fouling inception was observed.

  7. Three-Layer PE Corrosion-Inhibiting Coating for Steel Pipeline

    Institute of Scientific and Technical Information of China (English)

    Li Aiguo; Zheng Aijing

    1994-01-01

    @@ RIET (Research Institute of Engineering Technology of China National Petroleum Corporation)had got a lender contract for manufacturing corrosion-inhibiting coating for steel pipe piles through international competitive bidding in the extension section project of Dandong Port (China)in 1992. The contract had been completed by May 1993. Now, brief descriptions of the corrosion-inhibiting coating manufactured by RIETare presented as following.

  8. Calcium phosphate coating containing silver shows high antibacterial activity and low cytotoxicity and inhibits bacterial adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Yoshiki, E-mail: andoy@jmmc.jp [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Miyamoto, Hiroshi [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Noda, Iwao; Sakurai, Nobuko [Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Akiyama, Tomonori [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Yonekura, Yutaka; Shimazaki, Takafumi; Miyazaki, Masaki; Mawatari, Masaaki; Hotokebuchi, Takao [Department of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan)

    2010-01-01

    Surgical site infection is one of the serious complications of orthopedic implants. In order to reduce the incidence of implant-associated infections, we developed a novel coating technology of calcium phosphate (CP) containing silver (Ag), designated Ag-CP coating, using a thermal spraying technique. In this study, we evaluated the antibacterial efficacy and biological safety of this coating. In vitro antibacterial activity tests showed that the growths of Escherichia coli, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) are completely suppressed on Ag-CP coating. In vitro bacterial adherence tests revealed that the number of adherent bacteria on the surface of this coating is significantly less (p < 0.02) than that on the surface of the CP coating. Moreover, the Ag-CP coating completely inhibits MRSA adhesion [<10 colony-forming units (CFU)] when 10{sup 2} CFU MRSA is inoculated. On the other hand, V79 Chinese hamster lung cells were found to grow on the Ag-CP coating as well as on the CP coating in a cytotoxicity test. These results indicate that the Ag-CP coating on the surface of orthopedic implants exhibits antibacterial activity and inhibits bacterial adhesion without cytotoxicity.

  9. Less-Toxic Coatings for Inhibiting Corrosion of Aluminum

    Science.gov (United States)

    Minevski, Zoran; Clarke, Eric; Eylem, Cahit; Maxey, Jason; Nelson, Carl

    2003-01-01

    Two recently invented families of conversion- coating processes have been found to be effective in reducing or preventing corrosion of aluminum alloys. These processes offer less-toxic alternatives to prior conversion-coating processes that are highly effective but have fallen out of favor because they generate chromate wastes, which are toxic and carcinogenic. Specimens subjected to these processes were found to perform well in standard salt-fog corrosion tests.

  10. Thermoresponsive oligomers reduce Escherichia coli O157:H7 biofouling and virulence.

    Science.gov (United States)

    Lee, Jin-Hyung; Kim, Yong-Guy; Cho, Hyun Seob; Kim, Jintae; Kim, Seong-Cheol; Cho, Moo Hwan; Lee, Jintae

    2014-01-01

    Thermoresponsive polymers have potential biomedical applications for drug delivery and tissue engineering. Here, two thermoresponsive oligomers were synthesized, viz. oligo(N-isopropylacrylamide) (ONIPAM) and oligo(N-vinylcaprolactam) (OVCL), and their anti-biofouling abilities investigated against enterohemorrhagic E. coli O157:H7, which produces Shiga-like toxins and forms biofilms. Biofilm formation (biofouling) is closely related to E. coli O157:H7 infection and constitutes a major mechanism of antimicrobial resistance. The synthetic OVCL (MW 679) and three commercial OVCLs (up to MW 54,000) at 30 μg ml(-1) were found to inhibit biofouling by E. coli O157:H7 at 37 °C by more than 80% without adversely affecting bacterial growth. The anti-biofouling activity of ONIPAM was weaker than that of OVCL. However, at 25 °C, ONIPAM and OVCL did not affect E. coli O157:H7 biofouling. Transcriptional analysis showed that OVCL temperature-dependently downregulated curli genes in E. coli O157:H7, and this finding was in line with observed reductions in fimbriae production and biofouling. In addition, OVCL downregulated the Shiga-like toxin genes stx1 and stx2 in E. coli O157:H7 and attenuated its in vivo virulence in the nematode Caenorhabditis elegans. These results suggest that OVCL has potential use in antivirulence strategies against persistent E. coli O157:H7 infection.

  11. Antibiofilm activity of Bacillus pumilus SW9 against initial biofouling on microfiltration membranes.

    Science.gov (United States)

    Zhang, Ying; Yu, Xin; Gong, Song; Ye, Chengsong; Fan, Zihong; Lin, Huirong

    2014-02-01

    Membrane biofouling, resulting from biofilm formation on the membrane, has become the main obstacle hindering wider application of membrane technology. Initial biofouling proves to be crucial which involves early stages of microbial adhesion and biofilm formation. Biological control of microbial attachment seems to be a promising strategy due to its high efficiency and eco-friendliness. The present study investigated the effects of a bacterium Bacillus pumilus SW9 on controlling the initial fouling formed by four target bacterial strains which were pioneer species responsible for biofouling in membrane bioreactors, using microfiltration membranes as the abiotic surfaces. The results suggested that strain SW9 exhibited excellent antibiofilm activity by decreasing the attached biomass of target strains. The production of extracellular polysaccharides and proteins by four target strains was also reduced. A distinct improvement of permeate flux in dead-end filtration systems was achieved when introducing strain SW9 to microfiltration experiments. Scanning electron microscopy and confocal laser scanning microscopy were performed to further ascertain significant changes of the biofouling layers. A link between biofilm inhibition and initial biofouling mitigation was thus provided, suggesting an alternatively potential way to control membrane biofouling through bacterial interactions.

  12. Surface Functionalization of Polyethersulfone Membrane with Quaternary Ammonium Salts for Contact-Active Antibacterial and Anti-Biofouling Properties

    Directory of Open Access Journals (Sweden)

    Xiao Hu

    2016-05-01

    Full Text Available Biofilm is a significant cause for membrane fouling. Antibacterial-coated surfaces can inhibit biofilm formation by killing bacteria. In this study, polyethersulfone (PES microfiltration membrane was photografted by four antibiotic quaternary ammonium compounds (QACs separately, which were synthesized from dimethylaminoethyl methacrylate (DMAEMA by quaternization with butyl bromide (BB, octyl bromide (OB, dodecyl bromide (DB, or hexadecyl bromide (HB. XPS, ATR-FTIR, and SEM were used to confirm the surfaces’ composition and morphology. After modification, the pores on PES-g-DMAEMA-BB and PES-g-DMAEMA-OB were blocked, while PES-g-DMAEMA-DB and PES-g-DMAEMA-HB were retained. We supposed that DMAEMA-BB and DMAEMA-OB aggregated on the membrane surface due to the activities of intermolecular or intramolecular hydrogen bonds. Bacteria testing found the antibacterial activities of the membranes increased with the length of the substituted alkyl chain. Correspondingly, little bacteria were observed on PES-g-DMAEMA-DB and PES-g-DMAEMA-HB by SEM. The antifouling properties were investigated by filtration of a solution of Escherichia coli. Compared with the initial membrane, PES-g-DMAEMA-DB and PES-g-DMAEMA-HB showed excellent anti-biofouling performance with higher relative flux recovery (RFR of 88.3% and 92.7%, respectively. Thus, surface functionalization of the PES membrane with QACs can prevent bacteria adhesion and improve the anti-biofouling activity by the contact-active antibacterial property.

  13. Biofouling on PM stainless steels

    OpenAIRE

    García Ruiz, Ana María; Cisneros Belmonte, Manuel; Moreno Gómez, Diego Alejandro; Ruiz Román, José Manuel; García Cambronero, Luis Enrique

    2014-01-01

    Powder metallurgy (PM) consists in obtaining pieces of powder metal that are processed at high temperatures and pressure. Due to its characteristic manufacturing process, the materials can have a specific and controlled porosity, which makes it possible to obtain porous parts such as ball bearings, gears, and roller bearings, etc. This porosity is what made us think about how easy biofouling would be on these materials and its possible environmental applications.

  14. Progress in using conductive polymers as corrosion-inhibiting coatings

    International Nuclear Information System (INIS)

    A general review of the chemistry and corrosion control properties of electroactive polymers will be presented. These polymers are also known as conductive polymers (CPs), and this term will be used throughout this article. This paper will focus on both the synthesis of applicable CPs used for corrosion protection in various environments and their potential benefits over common organic barrier coatings

  15. Acidification of the cytosol inhibits endocytosis from coated pits

    OpenAIRE

    1987-01-01

    Acidification of the cytosol of a number of different cell lines strongly reduced the endocytic uptake of transferrin and epidermal growth factor. The number of transferrin binding sites at the cell surface was increased in acidified cells. Electron microscopic studies showed that the number of coated pits at the cell surface was not reduced in cells with acidified cytosol. Experiments with transferrin- horseradish peroxidase conjugates and a monoclonal anti-transferrin receptor antibody demo...

  16. In Situ Potentiometry and Ellipsometry: A Promising Tool to Study Biofouling of Potentiometric Sensors.

    Science.gov (United States)

    Lisak, Grzegorz; Arnebrant, Thomas; Lewenstam, Andrzej; Bobacka, Johan; Ruzgas, Tautgirdas

    2016-03-15

    In situ potentiometry and null ellipsometry was combined and used as a tool to follow the kinetics of biofouling of ion-selective electrodes (ISEs). The study was performed using custom-made solid-contact K(+)-ISEs consisting of a gold surface with immobilized 6-(ferrocenyl)hexanethiol as ion-to-electron transducer that was coated with a potassium-selective plasticized polymer membrane. The electrode potential and the ellipsometric signal (corresponding to the amount of adsorbed protein) were recorded simultaneously during adsorption of bovine serum albumin (BSA) at the surface of the K(+)-ISEs. This in situ method may become useful in developing sensors with minimized biofouling.

  17. Listeria monocytogenes inhibition by whey protein films and coatings incorporating lysozyme.

    Science.gov (United States)

    Min, Seacheol; Harris, Linda J; Han, Jung H; Krochta, John M

    2005-11-01

    The effects of whey protein isolate (WPI) films and coatings incorporating lysozyme (LZ) on the inhibition of Listeria monocytogenes both in and on microbial media, as well as on cold-smoked salmon, were studied. The antimicrobial effects of LZ were examined using various growth media by turbidity and plate counting tests. Disc-covering and disc-surface-spreading tests were also used to evaluate the effects of WPI films incorporating LZ. Smoked salmon was used as a model food to test the antimicrobial effects of WPI coatings incorporating LZ, both initially and during storage at 4 and 10 degrees C for 35 days. Tensile properties (elastic modulus, tensile strength, and percentage of elongation), oxygen permeability, and color (Hunter L, a, and b) of WPI films with and without LZ were also compared. LZ inhibited L. monocytogenes in broth and on agar media. The number of cells surviving after LZ treatments depended on the type of media. WPI films incorporating 204 mg of LZ per g of film (dry basis) inhibited the growth of a preparation of 4.4 log CFU/cm2 L. monocytogenes. WPI coatings prepared with 25 mg of LZ per g of coating solution initially inactivated more than 2.4, 4.5, and 3.0 log CFU/g of L. monocytogenes, total aerobes, and yeasts and molds in smoked salmon samples, respectively. The WPI coatings incorporating LZ efficiently retarded the growth of L. monocytogenes at both 4 and 10 degrees C. The anti-L. monocytogenes effect of LZ-WPI coating was more noticeable when the coating was applied before inoculation than when the coating was applied after inoculation. Significantly higher elastic modulus values and lower percentage of elongation and oxygen permeability values were measured with the WPI films incorporating LZ than with the plain WPI films.

  18. Calcium phosphate coating containing silver shows high antibacterial activity and low cytotoxicity and inhibits bacterial adhesion

    International Nuclear Information System (INIS)

    Surgical site infection is one of the serious complications of orthopedic implants. In order to reduce the incidence of implant-associated infections, we developed a novel coating technology of calcium phosphate (CP) containing silver (Ag), designated Ag-CP coating, using a thermal spraying technique. In this study, we evaluated the antibacterial efficacy and biological safety of this coating. In vitro antibacterial activity tests showed that the growths of Escherichia coli, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) are completely suppressed on Ag-CP coating. In vitro bacterial adherence tests revealed that the number of adherent bacteria on the surface of this coating is significantly less (p 2 CFU MRSA is inoculated. On the other hand, V79 Chinese hamster lung cells were found to grow on the Ag-CP coating as well as on the CP coating in a cytotoxicity test. These results indicate that the Ag-CP coating on the surface of orthopedic implants exhibits antibacterial activity and inhibits bacterial adhesion without cytotoxicity.

  19. Membrane Tension Inhibits Deformation by Coat Proteins in Clathrin-Mediated Endocytosis

    Science.gov (United States)

    Hassinger, Julian; Drubin, David; Oster, George; Rangamani, Padmini

    2016-02-01

    In clathrin-mediated endocytosis (CME), clathrin and various adaptor proteins coat a patch of the plasma membrane, which is reshaped to form a budded vesicle. Experimental studies have demonstrated that elevated membrane tension can inhibit bud formation by a clathrin coat. In this study, we investigate the impact of membrane tension on the mechanics of membrane budding by simulating clathrin coats that either grow in area or progressively induce greater curvature. At low membrane tension, progressively increasing the area of a curvature-generating coat causes the membrane to smoothly evolve from a flat to budded morphology, whereas the membrane remains essentially flat at high membrane tensions. Interestingly, at physiologically relevant, intermediate membrane tensions, the shape evolution of the membrane undergoes a snapthrough instability in which increasing coat area causes the membrane to "snap" from an open, U-shaped bud to a closed, $\\Omega$-shaped bud. This instability is accompanied by a large energy barrier, which could cause a developing endocytic pit to stall if the binding energy of additional coat is insufficient to overcome this barrier. Similar results were found for a coat of constant area in which the spontaneous curvature progressively increases. Additionally, a pulling force on the bud, simulating a force from actin polymerization, is sufficient to drive a transition from an open to closed bud, overcoming the energy barrier opposing this transition.

  20. Inhibition of biofilm formation and antibacterial properties of a silver nano-coating on human dentine.

    Science.gov (United States)

    Besinis, Alexandros; De Peralta, Tracy; Handy, Richard D

    2014-11-01

    The survival of pathogenic bacteria in the oral cavity depends on their successful adhesion to dental surfaces and their ability to develop into biofilms, known as dental plaque. Bacteria from the dental plaque are responsible for the development of dental caries, gingivitis, periodontitis, stomatitis and peri-implantitis. Certain metal nanoparticles have been suggested for infection control and the management of the oral biofilm. Here, it is shown that application of a silver nano-coating directly on dentine can successfully prevent the biofilm formation on dentine surfaces as well as inhibit bacterial growth in the surrounding media. This silver nano-coating was found to be stable (>98.8%) and to maintain its integrity in biological fluids. Its antibacterial activity was compared to silver nitrate and the widely used clinical antiseptic, chlorhexidine. The bacterial growth and cell viability were quantitatively assessed by measuring the turbidity, proportion of live and dead cells and lactate production. All three bioassays showed that silver nanoparticles and silver nitrate dentine coatings were equally highly bactericidal (>99.5%), while inhibiting bacterial adhesion. However, the latter caused significant dentine discolouration (ΔE* = 50.3). The chlorhexidine coating showed no antibacterial effect. Thus, silver nanoparticles may be a viable alternative to both chlorhexidine and silver nitrate, protecting from dental plaque and secondary caries when applied as a dentine coating, while they may provide the platform for creating anti-biofilm surfaces in medical devices and other biomedical applications. PMID:23875717

  1. Comparing Biofouling Control Treatments for Use on Aquaculture Nets

    Directory of Open Access Journals (Sweden)

    Geoffrey Swain

    2014-12-01

    Full Text Available Test panels comprised of uncoated, copper coated and silicone coated 7/8'' (22 mm mesh knitted nylon net were evaluated to compare their properties and the effectiveness to prevent biofouling. This paper describes test procedures that were developed to quantify the performance in terms of antifouling, cleanability, drag and cost. The copper treatment was the most effective at controlling fouling, however, the silicone treated nets were the easiest to clean. The drag forces on the net were a function of twine diameter, twine roughness and fouling. After immersion, the uncoated nets had the most drag followed by the silicone and copper treatments. The cost of applying silicone to nets is high; however, improved formulations may provide a non-toxic alternative to control fouling.

  2. Comparing biofouling control treatments for use on aquaculture nets.

    Science.gov (United States)

    Swain, Geoffrey; Shinjo, Nagahiko

    2014-12-02

    Test panels comprised of uncoated, copper coated and silicone coated 7/8'' (22 mm) mesh knitted nylon net were evaluated to compare their properties and the effectiveness to prevent biofouling. This paper describes test procedures that were developed to quantify the performance in terms of antifouling, cleanability, drag and cost. The copper treatment was the most effective at controlling fouling, however, the silicone treated nets were the easiest to clean. The drag forces on the net were a function of twine diameter, twine roughness and fouling. After immersion, the uncoated nets had the most drag followed by the silicone and copper treatments. The cost of applying silicone to nets is high; however, improved formulations may provide a non-toxic alternative to control fouling.

  3. Effect of anti-biofouling potential of multi-walled carbon nanotubes-filled polydimethylsiloxane composites on pioneer microbial colonization.

    Science.gov (United States)

    Sun, Yuan; Lang, Yanhe; Sun, Qian; Liang, Shuang; Liu, Yongkang; Zhang, Zhizhou

    2016-09-01

    In this paper, two carbon nanotube (CNT) nanofillers, namely the multi-walled carbon nanotubes (MWCNTs) and the carboxyl-modified MWCNTs (cMWCNTs), were introduced into the polydimethylsiloxane (PDMS) matrix respectively, in order to produce the PDMS composites with reinforced anti-biofouling properties. The anti-biofouling capacity of the silicone-based coatings, including the unfilled PDMS (P0), the MWCNTs-filled PDMS (PM) and the cMWCNTs-filled PDMS (PC), was examined via the field assays conducted in Weihai, China. The effect of different silicone-based coatings on the dynamic variations of the pioneer microbial-community diversity was analyzed using the single-strand conformation polymorphism (SSCP) technique. The PM and PC surfaces have exhibited excellent anti-biofouling properties in contrast to that of the PDMS surface, with extremely low attachment of the early colonizers, such as juvenile invertebrates, seaweeds and algae sporelings. The PM and PC surfaces can effectively prevent biofouling for more than 12 weeks. These combined results suggest that the incorporation of MWCNTs or cMWCNTs into the PDMS matrix can dramatically reinforce its anti-biofouling properties. The SSCP analysis reveals that compared with the PDMS surfaces, the PM and PC surfaces have strong modulating effect on the pioneer prokaryotic and eukaryotic communities, particularly on the colonization of pioneer eukaryotic microbes. The significantly reduced pioneer eukaryotic-community diversity may contribute to the weakening of the subsequent colonization of macrofoulers. PMID:27137800

  4. Effect of anti-biofouling potential of multi-walled carbon nanotubes-filled polydimethylsiloxane composites on pioneer microbial colonization.

    Science.gov (United States)

    Sun, Yuan; Lang, Yanhe; Sun, Qian; Liang, Shuang; Liu, Yongkang; Zhang, Zhizhou

    2016-09-01

    In this paper, two carbon nanotube (CNT) nanofillers, namely the multi-walled carbon nanotubes (MWCNTs) and the carboxyl-modified MWCNTs (cMWCNTs), were introduced into the polydimethylsiloxane (PDMS) matrix respectively, in order to produce the PDMS composites with reinforced anti-biofouling properties. The anti-biofouling capacity of the silicone-based coatings, including the unfilled PDMS (P0), the MWCNTs-filled PDMS (PM) and the cMWCNTs-filled PDMS (PC), was examined via the field assays conducted in Weihai, China. The effect of different silicone-based coatings on the dynamic variations of the pioneer microbial-community diversity was analyzed using the single-strand conformation polymorphism (SSCP) technique. The PM and PC surfaces have exhibited excellent anti-biofouling properties in contrast to that of the PDMS surface, with extremely low attachment of the early colonizers, such as juvenile invertebrates, seaweeds and algae sporelings. The PM and PC surfaces can effectively prevent biofouling for more than 12 weeks. These combined results suggest that the incorporation of MWCNTs or cMWCNTs into the PDMS matrix can dramatically reinforce its anti-biofouling properties. The SSCP analysis reveals that compared with the PDMS surfaces, the PM and PC surfaces have strong modulating effect on the pioneer prokaryotic and eukaryotic communities, particularly on the colonization of pioneer eukaryotic microbes. The significantly reduced pioneer eukaryotic-community diversity may contribute to the weakening of the subsequent colonization of macrofoulers.

  5. Inhibited growth of Pseudomonas aeruginosa by dextran- and polyacrylic acid-coated ceria nanoparticles

    Directory of Open Access Journals (Sweden)

    Wang Q

    2013-08-01

    Full Text Available Qi Wang,1 J Manuel Perez,2 Thomas J Webster1,3 1Bioengineering Program, College of Engineering, Northeastern University, Boston, MA, USA; 2Nanoscience Technology Center, University of Central Florida, Orlando, FL, USA; 3Department of Chemical Engineering, College of Engineering, Northeastern University, Boston, MA, USA Abstract: Ceria (CeO2 nanoparticles have been widely studied for numerous applications, but only a few recent studies have investigated their potential applications in medicine. Moreover, there have been almost no studies focusing on their possible antibacterial properties, despite the fact that such nanoparticles may reduce reactive oxygen species. In this study, we coated CeO2 nanoparticles with dextran or polyacrylic acid (PAA because of their enhanced biocompatibility properties, minimized toxicity, and reduced clearance by the immune system. For the first time, the coated CeO2 nanoparticles were tested in bacterial assays involving Pseudomonas aeruginosa, one of the most significant bacteria responsible for infecting numerous medical devices. The results showed that CeO2 nanoparticles with either coating significantly inhibited the growth of Pseudomonas aeruginosa, by up to 55.14%, after 24 hours compared with controls (no particles. The inhibition of bacterial growth was concentration dependent. In summary, this study revealed, for the first time, that the characterized dextran- and PAA-coated CeO2 nanoparticles could be potential novel materials for numerous antibacterial applications. Keywords: antibacterial, biomedical applications

  6. Potential biocontrol agents for biofouling on artificial structures.

    Science.gov (United States)

    Atalah, Javier; Newcombe, Emma M; Hopkins, Grant A; Forrest, Barrie M

    2014-09-01

    The accumulation of biofouling on coastal structures can lead to operational impacts and may harbour problematic organisms, including non-indigenous species. Benthic predators and grazers that can supress biofouling, and which are able to be artificially enhanced, have potential value as augmentative biocontrol agents. The ability of New Zealand native invertebrates to control biofouling on marina pontoons and wharf piles was tested. Caging experiments evaluated the ability of biocontrol to mitigate established biofouling, and to prevent fouling accumulation on defouled surfaces. On pontoons, the gastropods Haliotis iris and Cookia sulcata reduced established biofouling cover by >55% and largely prevented the accumulation of new biofouling over three months. On wharf piles C. sulcata removed 65% of biofouling biomass and reduced its cover by 73%. C. sulcata also had better retention and survival rates than other agents. Augmentative biocontrol has the potential to be an effective method to mitigate biofouling on marine structures.

  7. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

    Science.gov (United States)

    Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-10-01

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.

  8. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel.

    Science.gov (United States)

    Tesler, Alexander B; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-10-20

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.

  9. A simple approach to constructing antibacterial and anti-biofouling nanofibrous membranes.

    Science.gov (United States)

    Mei, Yan; Yao, Chen; Li, Xinsong

    2014-01-01

    In this work, antibacterial and anti-adhesive polymeric thin films were constructed on polyacrylonitrile (PAN) nanofibrous membranes in order to extend their applications. Polyhexamethylene guanidine hydrochloride (PHGH) as an antibacterial agent and heparin (HP) as an anti-adhesive agent have been successfully coated onto the membranes via a layer-by-layer (LBL) assembly technique confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), energy-dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The antibacterial properties of LBL-functionalized PAN nanofibrous membranes were evaluated using the Gram-positive bacterium Staphylococcus aureus and the Gram-negative Escherichia coli. Furthermore, the dependence of the antibacterial activity and anti-biofouling performance on the number of layers in the LBL films was investigated quantitatively. It was found that these LBL-modified nanofibrous membranes possessed high antibacterial activities, easy-cleaning properties and stability under physiological conditions, thus qualifying them as candidates for anti-biofouling coatings.

  10. Anti-Biofouling Effect of PEG-Grafted Block Copolymer Synthesized by RAFT Polymerization.

    Science.gov (United States)

    Kim, Seon-Mi; Han, Sang Suk; Kim, A Young; Choi, Beom-Jin; Paik, Hyun-Jong; Lee, Inwon; Park, Hyun; Chun, Ho Hwan; Cho, Youngjin; Hwang, Do-Hoon

    2015-10-01

    Poly(glycidyl methadrylate-block-styrene) (PGMA-b-PS), a block copolymer consisting of glycidyl methacrylate and styrene, was synthesized via reversible addition-fragmentation chain transfer living polymerization. The synthesized PGMA-b-PS was then grafted with low-molecular-weight polyethylene glycol (PEG) via epoxy ring opening to give PGMA-g-PEG-b-PS, which was evaluated as an anti-biofouling coating material. As a preliminary test for the anti-biofouling effect, a protein adsorption experiment was performed on the synthesized block copolymer surface. The block copolymers were spin-coated onto silicon wafers, and protein adsorption experiments were carried out using fluorescein isothiocyanate conjugate-labeled bovine serum albumin. The fluorescence intensity of the protein adsorbed on the block copolymer surface was compared with that of a polystyrene film as a reference. The synthesized PGMA-g-PEG-b-PS film showed much lower fluorescence intensity than that of the PS film.

  11. Inhibition of microbial concrete corrosion by Acidithiobacillus thiooxidans with functionalised zeolite-A coating.

    Science.gov (United States)

    Haile, Tesfaalem; Nakhla, George

    2009-01-01

    The inhibition of the corrosive action of Acidithiobacillus thiooxidans on concrete specimens coated by functionalised zeolite-A containing 14% zinc and 5% silver by weight was studied. Uncoated concrete specimens, epoxy-coated concrete specimens (EP), and functionalised zeolite-A coated concrete specimens with epoxy to zeolite weight ratios of 3:1 (Z1), 2:2 (Z2) and 1:3 (Z3) were studied. Specimens were characterised by x-ray powder diffraction and field emission scanning electron microscopy for the identification of corrosion products and morphological changes. Biomass growth at the conclusion of the 32-day experiments was 4, 179 and 193 mg volatile suspended solids g(-1) sulphur for the uncoated, EP and Z1 specimens, whereas that of Z2 and Z3 were negligible. In the uncoated, EP and Z1 specimens, sulphate production rates were 0.83, 9.1 and 8.8 mM SO(4)(2-) day(-1) and the specific growth rates, mu, were 0.14, 0.57 and 0.47 day(-1), respectively. The corresponding values for Z2 and Z3 were negligible due to their bacterial inhibition characteristics. PMID:18846450

  12. Inhibition of pyrite oxidation by surface coating agents: Batch and field studies

    Science.gov (United States)

    Choi, Jaeyoung; Do Gee, Eun; Yun, Hyun-Shik; Ram Lee, Woo; Park, Young-Tae

    2013-04-01

    The potential of several surface coating agents to inhibit the oxidation of metal sulfide minerals from Young-Dong coal mine and the Il-Gwang gold mine was examined by conducting laboratory scale batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH2PO4, MgO and KMnO4 as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H2O2 or NaClO). For the observed time period (8 days), Young-Dong coal mine samples exhibited the least sulfate (SO42-) production in the presence of KMnO4 (16%) or cement (4%) while, for Il-Gwang mine samples, the least SO42- production was observed in presence of KH2PO4 (8%) or cement (2%) compared to control. Field-scale pilot tests at the Il-Gwang site also showed that addition of KH2PO4 decreased SO42- production from 200 to 13 mg L-1 and it also reduced Cu and Mn from 8 and 3 mg L-1, respectively to detection limits). The experimental results suggested that the use of surface coating agents is a promising alternative for sulfide oxidation inhibition at acid mine drainage sites.

  13. Inhibition of sulfide mineral oxidation by surface coating agents: batch and field studies.

    Science.gov (United States)

    Ji, Min-Kyu; Gee, Eun-Do; Yun, Hyun-Shik; Lee, Woo-Ram; Park, Young-Tae; Khan, Moonis Ali; Jeon, Byong-Hun; Choi, Jaeyoung

    2012-08-30

    The potential of several surface coating agents to inhibit the oxidation of metal sulfide minerals from Young-Dong coal mine and the Il-Gwang gold mine was examined by conducting laboratory scale batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH(2)PO(4), MgO and KMnO(4) as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H(2)O(2) or NaClO). For the observed time period (8 days), Young-Dong coal mine samples exhibited the least sulfate (SO(4)(2-)) production in the presence of KMnO(4) (16%) or cement (4%) while, for Il-Gwang mine samples, the least SO(4)(2-) production was observed in presence of KH(2)PO(4) (8%) or cement (2%) compared to control. Field-scale pilot tests at the Il-Gwang site also showed that addition of KH(2)PO(4) decreased SO(4)(2-) production from 200 to 13 mg L(-1) and it also reduced Cu and Mn from 8 and 3 mg L(-1), respectively to detection limits). The experimental results suggested that the use of surface coating agents is a promising alternative for sulfide oxidation inhibition at acid mine drainage sites. PMID:22727481

  14. Inhibition of microbial concrete corrosion by Acidithiobacillus thiooxidans with functionalised zeolite-A coating.

    Science.gov (United States)

    Haile, Tesfaalem; Nakhla, George

    2009-01-01

    The inhibition of the corrosive action of Acidithiobacillus thiooxidans on concrete specimens coated by functionalised zeolite-A containing 14% zinc and 5% silver by weight was studied. Uncoated concrete specimens, epoxy-coated concrete specimens (EP), and functionalised zeolite-A coated concrete specimens with epoxy to zeolite weight ratios of 3:1 (Z1), 2:2 (Z2) and 1:3 (Z3) were studied. Specimens were characterised by x-ray powder diffraction and field emission scanning electron microscopy for the identification of corrosion products and morphological changes. Biomass growth at the conclusion of the 32-day experiments was 4, 179 and 193 mg volatile suspended solids g(-1) sulphur for the uncoated, EP and Z1 specimens, whereas that of Z2 and Z3 were negligible. In the uncoated, EP and Z1 specimens, sulphate production rates were 0.83, 9.1 and 8.8 mM SO(4)(2-) day(-1) and the specific growth rates, mu, were 0.14, 0.57 and 0.47 day(-1), respectively. The corresponding values for Z2 and Z3 were negligible due to their bacterial inhibition characteristics.

  15. Inhibition of the surface levelling of thermosetting polyester powder coatings caused by surface tension gradients

    OpenAIRE

    Zhao, Y.; Carey, JD; Knoops, N; Maetens, D; Hopkinson, I; Hay, JN; Keddie, JL

    2002-01-01

    Previous theoretical and experimental work has shown that surface tension gradients in liquid layers create surface defects and inhibit the levelling of an uneven surface. In coatings deposited from thermosetting polyester powders, which are studied here, small amounts of a low molecular-weight acrylate are incorporated to act as a “flow agent.” We find that this additive lowers the surface tension of the polymer melt and has a minor effect on the melt viscosity. A slower rate of levelling re...

  16. Control of marine biofouling and medical biofilm formation with engineered topography

    Science.gov (United States)

    Schumacher, James Frederick

    Biofouling is the unwanted accumulation and growth of cells and organisms on clean surfaces. This process occurs readily on unprotected surfaces in both the marine and physiological environments. Surface protection in both systems has typically relied upon toxic materials and biocides. Metallic paints, based on tin and copper, have been extremely successful as antifouling coatings for the hulls of ships by killing the majority of fouling species. Similarly, antibacterial medical coatings incorporate metal-containing compounds such as silver or antibiotics that kill the bacteria. The environmental concerns over the use of toxic paints and biocides in the ocean, the developed antibiotic resistance of bacterial biofilms, and the toxicity concerns with silver suggest the need for non-toxic and non-kill solutions for these systems. The manipulation of surface topography on non-toxic materials at the size scale of the fouling species or bacteria is one approach for the development of alternative coatings. These surfaces would function simply as a physical deterrent of settlement of fouling organisms or a physical obstacle for the adequate formation of a bacterial biofilm without the need to kill the targeted microorganisms. Species-specific topographical designs called engineered topographies have been designed, fabricated and evaluated for potential applications as antifouling marine coatings and material surfaces capable of reducing biofilm formation. Engineered topographies fabricated on the surface of a non-toxic, polydimethylsiloxane elastomer, or silicone, were shown to significantly reduce the attachment of zoospores of a common ship fouling green algae (Ulva) in standard bioassays versus a smooth substrate. Other engineered topographies were effective at significantly deterring the settlement of the cyprids of barnacles (Balanus amphitrite). These results indicate the potential use of engineered topography applied to non-toxic materials as an environmentally

  17. Control of biofouling on reverse osmosis polyamide membranes modified with biocidal nanoparticles and antifouling polymer brushes

    KAUST Repository

    Rahaman, Md. Saifur

    2014-01-01

    Thin-film composite (TFC) polyamide reverse osmosis (RO) membranes are prone to biofouling due to their inherent physicochemical surface properties. In order to address the biofouling problem, we have developed novel surface coatings functionalized with biocidal silver nanoparticles (AgNPs) and antifouling polymer brushes via polyelectrolyte layer-by-layer (LBL) self-assembly. The novel surface coating was prepared with polyelectrolyte LBL films containing poly(acrylic acid) (PAA) and poly(ethylene imine) (PEI), with the latter being either pure PEI or silver nanoparticles coated with PEI (Ag-PEI). The coatings were further functionalized by grafting of polymer brushes, using either hydrophilic poly(sulfobetaine) or low surface energy poly(dimethylsiloxane) (PDMS). The presence of both LBL films and sulfobetaine polymer brushes at the interface significantly increased the hydrophilicity of the membrane surface, while PDMS brushes lowered the membrane surface energy. Overall, all surface modifications resulted in significant reduction of irreversible bacterial cell adhesion. In microbial adhesion tests with E. coli bacteria, a normalized cell adhesion in the range of only 4 to 16% on the modified membrane surfaces was observed. Modified surfaces containing silver nanoparticles also exhibited strong antimicrobial activity. Membranes coated with LBL films of PAA/Ag-PEI achieved over 95% inactivation of bacteria attached to the surface within 1 hour of contact time. Both the antifouling and antimicrobial results suggest the potential of using these novel surface coatings in controlling the fouling of RO membranes. © The Royal Society of Chemistry 2014.

  18. Washing-resistant surfactant coated surface is able to inhibit pathogenic bacteria adhesion

    Science.gov (United States)

    Treter, Janine; Bonatto, Fernando; Krug, Cristiano; Soares, Gabriel Vieira; Baumvol, Israel Jacob Rabin; Macedo, Alexandre José

    2014-06-01

    Surface-active substances, which are able to organize themselves spontaneously on surfaces, triggering changes in the nature of the solid-liquid interface, are likely to influence microorganism adhesion and biofilm formation. Therefore, this study aimed to evaluate chemical non-ionic surfactants activity against pathogenic microbial biofilms and to cover biomaterial surfaces in order to obtain an anti-infective surface. After testing 11 different surfactants, Pluronic F127 was selected for further studies due to its non-biocidal properties and capability to inhibit up to 90% of biofilm formation of Gram-positive pathogen and its clinical isolates. The coating technique using direct impregnation on the surface showed important antibiofilm formation characteristics, even after extensive washes. Surface roughness and bacterial surface polarity does not influence the adhesion of Staphylococcus epidermidis, however, the material coated surface became extremely hydrophilic. The phenotype of S. epidermidis does not seem to have been affected by the contact with surfactant, reinforcing the evidence that a physical phenomenon is responsible for the activity. This paper presents a simple method of surface coating employing a synthetic surfactant to prevent S. epidermidis biofilm formation.

  19. Zinc oxide nanoparticle suspensions and layer-by-layer coatings inhibit staphylococcal growth.

    Science.gov (United States)

    McGuffie, Matthew J; Hong, Jin; Bahng, Joong Hwan; Glynos, Emmanouil; Green, Peter F; Kotov, Nicholas A; Younger, John G; VanEpps, J Scott

    2016-01-01

    Despite a decade of engineering and process improvements, bacterial infection remains the primary threat to implanted medical devices. Zinc oxide nanoparticles (ZnO-NPs) have demonstrated antimicrobial properties. Their microbial selectivity, stability, ease of production, and low cost make them attractive alternatives to silver NPs or antimicrobial peptides. Here we sought to (1) determine the relative efficacy of ZnO-NPs on planktonic growth of medically relevant pathogens; (2) establish the role of bacterial surface chemistry on ZnO-NP effectiveness; (3) evaluate NP shape as a factor in the dose-response; and (4) evaluate layer-by-layer (LBL) ZnO-NP surface coatings on biofilm growth. ZnO-NPs inhibited bacterial growth in a shape-dependent manner not previously seen or predicted. Pyramid shaped particles were the most effective and contrary to previous work, larger particles were more effective than smaller particles. Differential susceptibility of pathogens may be related to their surface hydrophobicity. LBL ZnO-NO coatings reduced staphylococcal biofilm burden by >95%. From the Clinical Editor: The use of medical implants is widespread. However, bacterial colonization remains a major concern. In this article, the authors investigated the use of zinc oxide nanoparticles (ZnO-NPs) to prevent bacterial infection. They showed in their experiments that ZnO-NPs significantly inhibited bacterial growth. This work may present a new alternative in using ZnO-NPs in medical devices. PMID:26515755

  20. Towards lightweight nanocomposite coatings for corrosion inhibition: Graphene, carbon nanotubes, and nanostructured magnesium as case studies

    Science.gov (United States)

    Dennis, Robert Vincent, III

    The field of nanocomposites is a burgeoning area of research due to the interest in the remarkable properties which can be achieved through their use in a variety of applications, including corrosion resistant coatings. Lightweighting is of increasing importance in the world today due to the ever growing push towards energy efficiency and the green movement and in recent years there has been a vast amount of research performed in the area of developing lightweight nanocomposites for corrosion inhibition. Many new composite materials have been developed through the use of newly developed nanomaterials (including carbonaceous and metallic constituents) and their specialized incorporation in the coating matrix materials. We start with a general review on the development of hybrid nanostructured composites for corrosion protection of base metals from a sustainability perspective in Chapter 1. This review demonstrates the ever swelling requirements for a paradigm shift in the way that we protect metals against corrosion due to the costs and environmental concerns that exist with currently used technology. In Chapter 2, we delve into the much required understanding of graphene oxide and reduced graphene oxide through near-edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements to elucidate information about the electronic structure upon incorporation of nitrogen within the structure. For successful integration of the carbonaceous nanomaterials into a composite coating, a full swath of knowledge is necessary. Within this work we have shown that upon chemical defunctionalization of graphene oxide to reduced graphene oxide by means of hydrazine treatment, nitrogen is incorporated into the structure in the form of a pyrazole ring. In Chapter 3, we demonstrate that by way of in situ polymerization, graphene and multiwalled carbon nanotubes can be incorporated within a polymer (polyetherimide, PEI) matrix. Two systems have been developed including graphene and

  1. Charged hydrophilic polymer brushes and their relevance for understanding marine biofouling.

    Science.gov (United States)

    Yandi, Wetra; Mieszkin, Sophie; di Fino, Alessio; Martin-Tanchereau, Pierre; Callow, Maureen E; Callow, James A; Tyson, Lyndsey; Clare, Anthony S; Ederth, Thomas

    2016-07-01

    The resistance of charged polymers to biofouling was investigated by subjecting cationic (PDMAEMA), anionic (PSPMA), neutral (PHEMA-co-PEG10MA), and zwitterionic (PSBMA) brushes to assays testing protein adsorption; attachment of the marine bacterium Cobetia marina; settlement and adhesion strength of zoospores of the green alga Ulva linza; settlement of barnacle (Balanus amphitrite and B. improvisus) cypris larvae; and field immersion tests. Several results go beyond the expected dependence on direct electrostatic attraction; PSPMA showed good resistance towards attachment of C. marina, low settlement and adhesion of U. linza zoospores, and significantly lower biofouling than on PHEMA-co-PEG10MA or PSBMA after a field test for one week. PDMAEMA showed potential as a contact-active anti-algal coating due to its capacity to damage attached spores. However, after field testing for eight weeks, there were no significant differences in biofouling coverage among the surfaces. While charged polymers are unsuitable as antifouling coatings in the natural environment, they provide valuable insights into fouling processes, and are relevant for studies due to charging of nominally neutral surfaces.

  2. Biofouling protection for marine environmental sensors

    Directory of Open Access Journals (Sweden)

    L. Delauney

    2010-05-01

    Full Text Available These days, many marine autonomous environment monitoring networks are set up in the world. These systems take advantage of existing superstructures such as offshore platforms, lightships, piers, breakwaters or are placed on specially designed buoys or underwater oceanographic structures. These systems commonly use various sensors to measure parameters such as dissolved oxygen, turbidity, conductivity, pH or fluorescence. Emphasis has to be put on the long term quality of measurements, yet sensors may face very short-term biofouling effects. Biofouling can disrupt the quality of the measurements, sometimes in less than a week.

    Many techniques to prevent biofouling on instrumentation are listed and studied by researchers and manufacturers. Very few of them are implemented on instruments and of those very few have been tested in situ on oceanographic sensors for deployment of at least one or two months.

    This paper presents a review of techniques used to protect against biofouling of in situ sensors and gives a short list and description of promising techniques.

  3. Biofouling protection for marine environmental sensors

    Science.gov (United States)

    Delauney, L.; Compère, C.; Lehaitre, M.

    2010-05-01

    These days, many marine autonomous environment monitoring networks are set up in the world. These systems take advantage of existing superstructures such as offshore platforms, lightships, piers, breakwaters or are placed on specially designed buoys or underwater oceanographic structures. These systems commonly use various sensors to measure parameters such as dissolved oxygen, turbidity, conductivity, pH or fluorescence. Emphasis has to be put on the long term quality of measurements, yet sensors may face very short-term biofouling effects. Biofouling can disrupt the quality of the measurements, sometimes in less than a week. Many techniques to prevent biofouling on instrumentation are listed and studied by researchers and manufacturers. Very few of them are implemented on instruments and of those very few have been tested in situ on oceanographic sensors for deployment of at least one or two months. This paper presents a review of techniques used to protect against biofouling of in situ sensors and gives a short list and description of promising techniques.

  4. Biomolecular and metagenomic analyses of biofouling communities

    Science.gov (United States)

    Despite the decades of research that have focused on understanding the formation of biofouling communities, relatively little is known about the soft fouling consortia that are responsible for their formation and function. In this study, we used PhyloChip microbial profiling, metagenomic DNA sequenc...

  5. Biofouling of spiral wound membrane systems

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.

    2009-01-01

    Biofouling of spiral wound membrane systems High quality drinking water can be produced with membrane filtration processes like reverse osmosis (RO) and nanofiltration (NF). Because the global demand for fresh clean water is increasing, these membrane technologies will increase in importance in the

  6. Spray- and spin-assisted layer-by-layer assembly of copper nanoparticles on thin-film composite reverse osmosis membrane for biofouling mitigation.

    Science.gov (United States)

    Ma, Wen; Soroush, Adel; Van Anh Luong, Tran; Brennan, Gregory; Rahaman, Md Saifur; Asadishad, Bahareh; Tufenkji, Nathalie

    2016-08-01

    Copper nanoparticles (CuNPs) have long been considered as highly effective biocides; however, the lack of suitable methods for loading CuNPs onto polymeric membranes is recognized as being one of the primary reasons for the limited research concerning their application in membrane industries. A highly efficient spray- and spin-assisted layer-by-layer (SSLbL) method was developed to functionalize the TFC polyamide RO membranes with controllable loading of CuNPs for biofouling control. The SSLbL method was able to produce a uniform bilayer of polyethyleneimine-coated CuNPs and poly(acrylic) acid in less than 1 min, which is far more efficient than the traditional dipping approach (25-60 min). The successful loading of CuNPs onto the membrane surface was confirmed by XPS analysis. Increasing the number of bilayers from 2 to 10 led to an increased quantity of CuNPs on the membrane surface, from 1.75 to 23.7 μg cm(-2). Multi-layer coating exhibited minor impact on the membrane water permeation flux (13.3% reduction) while retaining the original salt rejection ability. Both static bacterial inactivation and cross-flow filtration tests demonstrated that CuNPs could significantly improve anti-biofouling property of a polyamide membrane and effectively inhibit the permeate flux reduction caused by bacterial deposition on the membrane surface. Once depleted, CuNPs can also be potentially regenerated on the membrane surface via the same SSLbL method.

  7. Spray- and spin-assisted layer-by-layer assembly of copper nanoparticles on thin-film composite reverse osmosis membrane for biofouling mitigation.

    Science.gov (United States)

    Ma, Wen; Soroush, Adel; Van Anh Luong, Tran; Brennan, Gregory; Rahaman, Md Saifur; Asadishad, Bahareh; Tufenkji, Nathalie

    2016-08-01

    Copper nanoparticles (CuNPs) have long been considered as highly effective biocides; however, the lack of suitable methods for loading CuNPs onto polymeric membranes is recognized as being one of the primary reasons for the limited research concerning their application in membrane industries. A highly efficient spray- and spin-assisted layer-by-layer (SSLbL) method was developed to functionalize the TFC polyamide RO membranes with controllable loading of CuNPs for biofouling control. The SSLbL method was able to produce a uniform bilayer of polyethyleneimine-coated CuNPs and poly(acrylic) acid in less than 1 min, which is far more efficient than the traditional dipping approach (25-60 min). The successful loading of CuNPs onto the membrane surface was confirmed by XPS analysis. Increasing the number of bilayers from 2 to 10 led to an increased quantity of CuNPs on the membrane surface, from 1.75 to 23.7 μg cm(-2). Multi-layer coating exhibited minor impact on the membrane water permeation flux (13.3% reduction) while retaining the original salt rejection ability. Both static bacterial inactivation and cross-flow filtration tests demonstrated that CuNPs could significantly improve anti-biofouling property of a polyamide membrane and effectively inhibit the permeate flux reduction caused by bacterial deposition on the membrane surface. Once depleted, CuNPs can also be potentially regenerated on the membrane surface via the same SSLbL method. PMID:27161885

  8. Ph responsive capsules containing composite coatings for corrosion inhibition in metal alloys

    Science.gov (United States)

    Kashi, Kiran Bhat

    Hexavalent chromes have been used as effective corrosion inhibitors due to their high inhibitor efficiency and low cost for the protection of several metal alloys. However, owing to their toxicity federal legislations restrict the use and distribution of these highly toxic materials. The need for an environmentally friendly yet effective alternative to the chrome based corrosion inhibitors has led to the investigation of rare earth metals as potential candidates. Cerium is one such rare earth metal that has received considerable attention as an alternative to hexavalent chromes. However, the high water solubility of some of the cerium salts makes it difficult for the incorporation of such salts in coatings. In this work, pH responsive microcapsules containing cerium salts were synthesized using an internally phase separated emulsion polymerization technique. Core shell microcapsule consisting of a water core containing dissolved cerium salts were synthesized. The synthesized capsules were characterized using characterization techniques such as Fourier Transform Infrared (FTIR) spectroscopy, UV-vis spectroscopy, Dynamic Mechanical Analysis (DMA), Thermo-Gravimetric Analysis (TGA), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The structure and morphology of the capsules were studied using electron microscopy techniques. The synthesized capsules were dispersed in 2K epoxy coatings and applied on aluminum alloy 2024 T-3 and cold rolled steel substrates. These coatings were exposed to salt spray (ASTM B117) and electrochemically evaluated using electrochemical impedance spectroscopy (EIS), potentio-dynamic(PD) polarization, cyclic voltammetry(CV), open circuit potential(OCP) measurements. Localized corrosion assessment was also performed on the coated metal alloys using Scanning electrochemical microscopy (SECM) to understand the mechanism of corrosion inhibition using cerium encapsulated microcapsules.

  9. Biofouling and biocorrosion in industrial water systems.

    Science.gov (United States)

    Coetser, S E; Cloete, T E

    2005-01-01

    Corrosion associated with microorganisms has been recognized for over 50 years and yet the study of microbiologically influenced corrosion (MIC) is relatively new. MIC can occur in diverse environments and is not limited to aqueous corrosion under submerged conditions, but also takes place in humid atmospheres. Biofouling of industrial water systems is the phenomenon whereby surfaces in contact with water are colonized by microorganisms, which are ubiquitous in our environment. However, the economic implications of biofouling in industrial water systems are much greater than many people realize. In a survey conducted by the National Association of Corrosion Engineers of the United States ten years ago, it was found that many corrosion engineer did not accept the role of bacteria in corrosion, and many of then that did, could not recognize and mitigate the problem. Biofouling can be described in terms of its effects on processes and products such as material degradation (bio-corossion), product contamination, mechanical blockages, and impedance of heat transfer. Microorganisms distinguish themselves from other industrial water contaminants by their ability to utilize available nutrient sources, reproduce, and generate intra- and extracellular organic and inorganic substances in water. A sound understanding of the molecular and physiological activities of the microorganisms involved is necessary before strategies for the long term control of biofouling can be format. Traditional water treatment strategies however, have largely failed to address those factors that promote biofouling activities and lead to biocorrosion. Some of the major developments in recent years have been a redefinition of biofilm architecture and the realization that MIC of metals can be best understood as biomineralization.

  10. Coatings.

    Science.gov (United States)

    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)

  11. PROBLEMS OF BIOFOULING ON FISH–CAGE NETS IN AQUACULTURE

    OpenAIRE

    Merica Slišković; Gorana Jelić

    2002-01-01

    Biofouling on fish–cage netting is a serious technical and economical problem to aquaculture worldwide. Compensation for the effects of biofouling must be included in cage system design and planning, as fouling can dramatically increase both weight and drag. Settlements of sessile plants and animals, with accumulation of the detritus diminish the size of mesh and can rapidly occlude mesh. Negative effect of smaller mesh size is changing in water flow trough the cages. Biofouling problems nece...

  12. Environmentally Benign and Permanent Modifications to Prevent Biofouling on Marine and Hydrokinetic Devices

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Zhang

    2012-04-19

    Semprus Biosciences is developing environmentally benign and permanent modifications to prevent biofouling on Marine and Hydrokinetic (MHK) devices. Biofouling, including growth on external surfaces by bacteria, algae, barnacles, mussels, and other marine organisms, accumulate quickly on MHK devices, causing mechanical wear and changes in performance. Biofouling on crucial components of hydrokinetic devices, such as rotors, generators, and turbines, imposes substantial mass and hydrodynamic loading with associated efficiency loss and maintenance costs. Most antifouling coatings leach toxic ingredients, such as copper and tributyltin, through an eroding process, but increasingly stringent regulation of biocides has led to interest in the development of non-biocidal technologies to control fouling. Semprus Biosciences research team is developing modifications to prevent fouling from a broad spectrum of organisms on devices of all shapes, sizes, and materials for the life of the product. The research team designed and developed betaine-based polymers as novel underwater coatings to resist the attachment of marine organisms. Different betaine-based monomers and polymers were synthesized and incorporated within various coating formulations. The formulations and application methods were developed on aluminum panels with required adhesion strength and mechanical properties. The coating polymers were chemically stable under UV, hydrolytic and oxidative environments. The sulfobetaine formulations are applicable as nonleaching and stable underwater coatings. For the first time, coating formulations modified with highly packed sulfobetaine polymers were prepared and demonstrated resistance to a broad spectrum of marine organisms. Assays for comparing nonfouling performance were developed to evaluate protein adsorption and bacteria attachment. Barnacle settlement and removal were evaluated and a 60-day field test was performed. Silicone substrates including a commercial

  13. Study on interactions between suspended matter and biofouling formed by treated sewage.

    Science.gov (United States)

    Yang, Qianpeng; Chang, Siyuan; Shi, Lin

    2015-01-01

    Heat exchangers used for treated sewage energy recovery usually suffer from the composite fouling problem, which seriously impairs the heat transfer efficiency. Treated sewage heat exchanger composite fouling is mostly composed of biofouling and is notably affected by interactions between the biofouling and suspended matter. Experiments were performed using simulated treated sewage and two kinds of simulated suspended matter, silicon dioxide particles and polyamide filaments, to model the interactions. Different flow velocities, particle sizes and concentrations were tested with their influences presented by the fouling wet weight changes. Empirical equation and threshold were developed based on the results to predict whether the suspended matter promotes or impedes fouling growth. The results indicate that proper control of the flow velocities, particle sizes and concentrations of suspended matter using empirical equation and threshold can inhibit fouling by reducing unwanted positive interactions and promoting beneficial negative interactions. The filament interactions were analysed and the unique attachment mechanisms of filaments were discussed for the first time.

  14. A small-molecule norspermidine and norspermidine-hosting polyelectrolyte coatings inhibit biofilm formation by multi-species wastewater culture.

    Science.gov (United States)

    Si, Xiurong; Quan, Xiangchun; Wu, Yachuan

    2015-12-01

    Norspermidine is a potent and non-bactericidal small-molecule inhibitor of biofilm growth. In this study, impacts of norspermidine on biofilm control and existing biofilm dispersal by a mixed culture from wastewater treatment systems were investigated. A surface-mediated releasing approach for prevention of bacterial biofilm formation was established via encapsulating norspermidine into polyelectrolyte multilayer coatings. Results showed that the presence of norspermidine (500-1000 μM) in medium remarkably prevented biofilm formation. Norspermidine was also effective in disassembling pre-formed biofilms. Norspermidine-containing multilayer coatings were successfully fabricated on glass slides via layer-by-layer deposition in polyethylenimine (PEI) and poly(acrylic acid) (PAA) solution. This coating exhibited a high anti-biofilm property against a mixed culture and three pure strains (Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli). The loading amount and space distribution of norspermidine in the multilayer coating were key factors influencing its anti-biofilm efficacy. The polymer coating with norspermidine loaded in each bilayer (each-layer-type) exhibited better anti-biofilm efficacy than the bottom-type and the top-type coating, which showed a stable biofilm inhibition rate of about 60 % even after 5-day leaching in aqueous solution. Norspermidine could retard bacterial adhesion and destruct biofilm matrix by reducing exopolysaccharides and extracellular DNA (eDNA) associated with bacteria instead of growth inhibition. Norspermidine and the norspermidine-hosting coatings in this study offer a great potential for the control of biofilms in the settings of water purification and wastewater treatment systems, which shows the advantage of broad spectrum and less risk of evolved bacterial resistance compared to conventional microbicidal agents (e.g., antibiotics).

  15. A small-molecule norspermidine and norspermidine-hosting polyelectrolyte coatings inhibit biofilm formation by multi-species wastewater culture.

    Science.gov (United States)

    Si, Xiurong; Quan, Xiangchun; Wu, Yachuan

    2015-12-01

    Norspermidine is a potent and non-bactericidal small-molecule inhibitor of biofilm growth. In this study, impacts of norspermidine on biofilm control and existing biofilm dispersal by a mixed culture from wastewater treatment systems were investigated. A surface-mediated releasing approach for prevention of bacterial biofilm formation was established via encapsulating norspermidine into polyelectrolyte multilayer coatings. Results showed that the presence of norspermidine (500-1000 μM) in medium remarkably prevented biofilm formation. Norspermidine was also effective in disassembling pre-formed biofilms. Norspermidine-containing multilayer coatings were successfully fabricated on glass slides via layer-by-layer deposition in polyethylenimine (PEI) and poly(acrylic acid) (PAA) solution. This coating exhibited a high anti-biofilm property against a mixed culture and three pure strains (Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli). The loading amount and space distribution of norspermidine in the multilayer coating were key factors influencing its anti-biofilm efficacy. The polymer coating with norspermidine loaded in each bilayer (each-layer-type) exhibited better anti-biofilm efficacy than the bottom-type and the top-type coating, which showed a stable biofilm inhibition rate of about 60 % even after 5-day leaching in aqueous solution. Norspermidine could retard bacterial adhesion and destruct biofilm matrix by reducing exopolysaccharides and extracellular DNA (eDNA) associated with bacteria instead of growth inhibition. Norspermidine and the norspermidine-hosting coatings in this study offer a great potential for the control of biofilms in the settings of water purification and wastewater treatment systems, which shows the advantage of broad spectrum and less risk of evolved bacterial resistance compared to conventional microbicidal agents (e.g., antibiotics). PMID:26350146

  16. Fish gelatin combined with chitosan coating inhibits myofibril degradation of golden pomfret (Trachinotus blochii) fillet during cold storage.

    Science.gov (United States)

    Feng, Xiao; Bansal, Nidhi; Yang, Hongshun

    2016-06-01

    Coating of gelatin and chitosan can improve fish fillet's quality, but the mechanism is not clear. Chitosan/gelatin coatings significantly prevented deterioration of golden pomfret fillet at 4 °C. Chitosan with 7.2% gelatin group showed the best effect on preserving the length of myofibril, which remained greater than 15 μm at day 17 of storage, while for control, chitosan and chitosan combined with 3.6% gelatin group, it was 5.03, 10.04 and 9.02 μm, respectively. The MALDI-TOF MS result revealed that the coatings slowed down the protein deterioration of fillet. On days 13 and 17, the myosin light chain and myoglobin in control group degraded, while the two proteins still existed in chitosan/gelatin coated groups. Overall, the chitosan with 7.2% gelatin coating had the best effect on preserving fillet's quality during storage. The coating may exert its protective effect via inhibiting myofibril degradation within fillet. PMID:26830590

  17. N-acyl homoserine lactone-mediated quorum sensing with special reference to use of quorum quenching bacteria in membrane biofouling control.

    Science.gov (United States)

    Lade, Harshad; Paul, Diby; Kweon, Ji Hyang

    2014-01-01

    Membrane biofouling remains a severe problem to be addressed in wastewater treatment systems affecting reactor performance and economy. The finding that many wastewater bacteria rely on N-acyl homoserine lactone-mediated quorum sensing to synchronize their activities essential for biofilm formations; the quenching bacterial quorum sensing suggests a promising approach for control of membrane biofouling. A variety of quorum quenching compounds of both synthetic and natural origin have been identified and found effective in inhibition of membrane biofouling with much less environmental impact than traditional antimicrobials. Work over the past few years has demonstrated that enzymatic quorum quenching mechanisms are widely conserved in several prokaryotic organisms and can be utilized as a potent tool for inhibition of membrane biofouling. Such naturally occurring bacterial quorum quenching mechanisms also play important roles in microbe-microbe interactions and have been used to develop sustainable nonantibiotic antifouling strategies. Advances in membrane fabrication and bacteria entrapment techniques have allowed the implication of such quorum quenching bacteria for better design of membrane bioreactor with improved antibiofouling efficacies. In view of this, the present paper is designed to review and discuss the recent developments in control of membrane biofouling with special emphasis on quorum quenching bacteria that are applied in membrane bioreactors.

  18. N-Acyl Homoserine Lactone-Mediated Quorum Sensing with Special Reference to Use of Quorum Quenching Bacteria in Membrane Biofouling Control

    Directory of Open Access Journals (Sweden)

    Harshad Lade

    2014-01-01

    Full Text Available Membrane biofouling remains a severe problem to be addressed in wastewater treatment systems affecting reactor performance and economy. The finding that many wastewater bacteria rely on N-acyl homoserine lactone-mediated quorum sensing to synchronize their activities essential for biofilm formations; the quenching bacterial quorum sensing suggests a promising approach for control of membrane biofouling. A variety of quorum quenching compounds of both synthetic and natural origin have been identified and found effective in inhibition of membrane biofouling with much less environmental impact than traditional antimicrobials. Work over the past few years has demonstrated that enzymatic quorum quenching mechanisms are widely conserved in several prokaryotic organisms and can be utilized as a potent tool for inhibition of membrane biofouling. Such naturally occurring bacterial quorum quenching mechanisms also play important roles in microbe-microbe interactions and have been used to develop sustainable nonantibiotic antifouling strategies. Advances in membrane fabrication and bacteria entrapment techniques have allowed the implication of such quorum quenching bacteria for better design of membrane bioreactor with improved antibiofouling efficacies. In view of this, the present paper is designed to review and discuss the recent developments in control of membrane biofouling with special emphasis on quorum quenching bacteria that are applied in membrane bioreactors.

  19. Influence of GlidArc treatment on layers formation of biofouling

    Science.gov (United States)

    Hnatiuc, B.; Sabau, A.; Ghita, S.; Hnatiuc, M.; Dumitrache, C. L.; Pellerin, S.

    2015-02-01

    Corrosion in marine environment is a complex dynamic process influenced mainly by physical chemical, microbiological and mechanical parameters. Times for maintenance related to corrosion are greater than 80% of the total repair. Reducing this cost would be a significant saving, and an effective treatment can reduce times related to ships repairing. Biofouling is a main cause of corrosion and its formation contains four steps. To inhibit biofouling it is proposed a treatment based on non-thermal plasma produced by GlidArc, which can be applied before the immersion of small boats in the sea, as well as cleaning treatment of the hull after a period of time. This work presents the microbiological results of treatment of metal surfaces (naval OL36 steel) with GlidArc technology, according to the first, respectively the second phase formation of biofouling. Samples of naval steel were prepared with three specific naval paints and before the treatment have been introduced in seawater. Microbiological results have been compared for two types of treatments based on GlidArc. In the first case the painted samples are submitted to direct action of non-thermal plasma. In the second case the plasma produced by GlidArc technology is used to activate a solution (plasma activated water = PAW) and then the samples are introduced into this water.

  20. Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

    Science.gov (United States)

    Mohan, Arun Ram

    Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor

  1. Biofouling control: Bacterial quorum quenching versus chlorination in membrane bioreactors.

    Science.gov (United States)

    Weerasekara, Nuwan A; Choo, Kwang-Ho; Lee, Chung-Hak

    2016-10-15

    Biofilm formation (biofouling) induced via cell-to-cell communication (quorum sensing) causes problems in membrane filtration processes. Chorine is one of the most common chemicals used to interfere with biofouling; however, biofouling control is challenging because it is a natural process. This study demonstrates biofouling control for submerged hollow fiber membranes in membrane bioreactors by means of bacterial quorum quenching (QQ) using Rhodococcus sp. BH4 with chemically enhanced backwashing. This is the first trial to bring QQ alongside chlorine injection into practice. A high chlorine dose (100 mg/L as Cl2) to the system is insufficient for preventing biofouling, but addition of the QQ bacterium is effective for disrupting biofouling that cannot be achieved by chlorination alone. QQ reduces the biologically induced metal precipitate and extracellular biopolymer levels in the biofilm, and biofouling is significantly delayed when QQ is applied in addition to chlorine dosing. QQ with chlorine injection gives synergistic effects on reducing physically and chemically reversible fouling resistances while saving substantial filtration energy. Manipulating microbial community functions with chemical treatment is an attractive tool for biofilm dispersal in membrane bioreactors.

  2. Dynamic surface deformation of silicone elastomers for management of marine biofouling: laboratory and field studies using pneumatic actuation.

    Science.gov (United States)

    Shivapooja, Phanindhar; Wang, Qiming; Szott, Lizzy M; Orihuela, Beatriz; Rittschof, Daniel; Zhao, Xuanhe; López, Gabriel P

    2015-01-01

    Many strategies have been developed to improve the fouling release (FR) performance of silicone coatings. However, biofilms inevitably build on these surfaces over time. Previous studies have shown that intentional deformation of silicone elastomers can be employed to detach biofouling species. In this study, inspired by the methods used in soft-robotic systems, controlled deformation of silicone elastomers via pneumatic actuation was employed to detach adherent biofilms. Using programmed surface deformation, it was possible to release > 90% of biofilm from surfaces in both laboratory and field environments. A higher substratum strain was required to remove biofilms accumulated in the field environment as compared with laboratory-grown biofilms. Further, the study indicated that substratum modulus influences the strain needed to de-bond biofilms. Surface deformation-based approaches have potential for use in the management of biofouling in a number of technological areas, including in niche applications where pneumatic actuation of surface deformation is feasible.

  3. Modification of Silicone Elastomer Surfaces with Zwitterionic Polymers: Short-Term Fouling Resistance and Triggered Biofouling Release.

    Science.gov (United States)

    Shivapooja, Phanindhar; Yu, Qian; Orihuela, Beatriz; Mays, Robin; Rittschof, Daniel; Genzer, Jan; López, Gabriel P

    2015-11-25

    We present a method for dual-mode-management of biofouling by modifying surface of silicone elastomers with zwitterionic polymeric grafts. Poly(sulfobetaine methacrylate) was grafted from poly(vinylmethylsiloxane) elastomer substrates using thiol-ene click chemistry and surface-initiated, controlled radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionality. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. Such dual-functional surfaces may be useful in developing environmentally and biologically friendly coatings for biofouling management on marine, industrial, and biomedical equipment because they can obviate the use of toxic compounds.

  4. Novel Self-Cleaning Surfaces for Biofouling Prevention Project

    Data.gov (United States)

    National Aeronautics and Space Administration — One of the most problematic issues that facing efficient water reclamation processes for long duration space missions is biofilm growth and biofouling on RO...

  5. INVESTIGATIONS INTO BIOFOULING PHENOMENA IN FINE PORE AERATION DEVICES

    Science.gov (United States)

    Microbiologically-based procedures were used to describe biofouling phenomena on fine pore aeration devices and to determine whether biofilm characteristics could be related to diffuser process performance parameters. Fine pore diffusers were obtained from five municipal wastewa...

  6. Biofouling Organisms in the Field and for the Classroom.

    Science.gov (United States)

    Stout, Prentice K.

    1983-01-01

    Biofouling organisms are marine organisms that affix themselves to navigational buoys, floating docks, and pilings. Techniques for collecting these organisms for classroom use are described. General background information on the organisms and a list of common species are included. (JN)

  7. Fouling in your own nest: vessel noise increases biofouling.

    Science.gov (United States)

    Stanley, Jenni A; Wilkens, Serena L; Jeffs, Andrew G

    2014-01-01

    Globally billions of dollars are spent each year on attempting to reduce marine biofouling on commercial vessels, largely because it results in higher fuel costs due to increased hydrodynamic drag. Biofouling has been long assumed to be primarily due to the availability of vacant space on the surface of the hull. Here, it is shown that the addition of the noise emitted through a vessel's hull in port increases the settlement and growth of biofouling organisms within four weeks of clean surfaces being placed in the sea. More than twice as many bryozoans, oysters, calcareous tube worms and barnacles settled and established on surfaces with vessel noise compared to those without. Likewise, individuals from three species grew significantly larger in size in the presence of vessel noise. The results demonstrate that vessel noise in port is promoting biofouling on hulls and that underwater sound plays a much wider ecological role in the marine environment than was previously considered possible.

  8. Variation in biofouling on different species of Indian timbers

    Digital Repository Service at National Institute of Oceanography (India)

    Raveendran, T.V.; Wagh, A.B.

    Biofouling on twenty species of wood exposed in waters of Mormugao Harbour, Goa, India have been presented. Macrofouling biomass varied from species to species. Maximum biomass was recorded on Artocarpus chaplasha (4 kg/m2) and minimum on Hopea...

  9. Biofouling-resilient nanoporous gold electrodes for DNA sensing.

    Science.gov (United States)

    Daggumati, Pallavi; Matharu, Zimple; Wang, Ling; Seker, Erkin

    2015-09-01

    Electrochemical nucleic acid sensors are promising tools for point-of-care diagnostic platforms with their facile integration with electronics and scalability. However, nucleic acid detection in complex biological fluids is challenging as biomolecules nonspecifically adsorb on the electrode surface and adversely affect the sensor performance by obscuring the transport of analytes and redox species to the electrode. We report that nanoporous gold (np-Au) electrodes, prepared by a microfabrication-compatible self-assembly process and functionalized with DNA probes, enabled detection of target DNA molecules (10-200 nM) in physiologically relevant complex media (bovine serum albumin and fetal bovine serum). In contrast, the sensor performance was compromised for planar gold electrodes in the same conditions. Hybridization efficiency decreased by 10% for np-Au with coarser pores revealing a pore-size dependence of sensor performance in biofouling conditions. This nanostructure-dependent functionality in complex media suggests that the pores with the optimal size and geometry act as sieves for blocking the biomolecules from inhibiting the surfaces within the porous volume while allowing the transport of nucleic acid analytes and redox molecules.

  10. Linking ceragenins to water-treatment membranes to minimize biofouling.

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael R.; Altman, Susan Jeanne; Feng, Yanshu (Brigham Young University, Provo, Utah); Savage, Paul B. (Brigham Young University, Provo, Utah); Pollard, Jacob (Brigham Young University, Provo, Utah); Branda, Steven S.; Goeres, Darla (Montana State University, Bozeman, MT); Buckingham-Meyer, Kelli (Montana State University, Bozeman, MT); Stafslien, Shane (North Dakota State University, Fargo, ND); Marry, Christopher; Jones, Howland D. T.; Lichtenberger, Alyssa; Kirk, Matthew F.; McGrath, Lucas K. (LMATA, Albuquerque, NM)

    2012-01-01

    Ceragenins were used to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced antimicrobial peptide mimics that display broad-spectrum bactericidal activity. While ceragenins have been used on bio-medical devices, use of ceragenins on water-treatment membranes is novel. Biofouling impacts membrane separation processes for many industrial applications such as desalination, waste-water treatment, oil and gas extraction, and power generation. Biofouling results in a loss of permeate flux and increase in energy use. Creation of biofouling resistant membranes will assist in creation of clean water with lower energy usage and energy with lower water usage. Five methods of attaching three different ceragenin molecules were conducted and tested. Biofouling reduction was observed in the majority of the tests, indicating the ceragenins are a viable solution to biofouling on water treatment membranes. Silane direct attachment appears to be the most promising attachment method if a high concentration of CSA-121a is used. Additional refinement of the attachment methods are needed in order to achieve our goal of several log-reduction in biofilm cell density without impacting the membrane flux. Concurrently, biofilm forming bacteria were isolated from source waters relevant for water treatment: wastewater, agricultural drainage, river water, seawater, and brackish groundwater. These isolates can be used for future testing of methods to control biofouling. Once isolated, the ability of the isolates to grow biofilms was tested with high-throughput multiwell methods. Based on these tests, the following species were selected for further testing in tube reactors and CDC reactors: Pseudomonas ssp. (wastewater, agricultural drainage, and Colorado River water), Nocardia coeliaca or Rhodococcus spp. (wastewater), Pseudomonas fluorescens and Hydrogenophaga palleronii (agricultural drainage), Sulfitobacter donghicola, Rhodococcus fascians, Rhodobacter

  11. New approaches to characterizing and understanding biofouling of spiral wound membrane systems

    KAUST Repository

    van Loosdrecht, Mark C.M.

    2012-06-01

    Historically, biofouling research on spiral wound membrane systems is typically problem solving oriented. Membrane modules are studied as black box systems, investigated by autopsies. Biofouling is not a simple process. Many factors influence each other in a non-linear fashion. These features make biofouling a subject which is not easy to study using a fundamental scientific approach. Nevertheless to solve or minimize the negative impacts of biofouling, a clear understanding of the interacting basic principles is needed. Recent research into microbiological characterizing of biofouling, small scale test units, application of in situ visualization methods, and model approaches allow such an integrated study of biofouling. © IWA Publishing 2012.

  12. Nanocomposite strategies for limiting medical and marine biofouling

    Science.gov (United States)

    Cooper, Scott Patrick

    are likely caused by various rates of silicate hydrolysis, condensation, and hydrogen bonding to PVP. Viscosity of the sol plays little role in determining the diameter of the dried microspheres. An antibiotic, vancomycin, is successfully incorporated into these hybrid microspheres. Vancomycin is released for 5-7 days as measured by UV absorption. An in vitro assay against cultures of Staphylococcus aureus demonstrates that the drug remains effective for 4 days. Marine biofouling is addressed by imparting topography onto silica-reinforced poly(dimethylsiloxane) elastomeric (PDMSe) films. Swimming zoospores from the green alga Ulva are used as a model fouling organism. A bio-inspired topography deterred attachment of the zoospores by 70-80% over a 4-hr assay. Image analysis of the zoospores suggests that the topography may inhibit biofilm formation by disrupting the early-stage aggregation of spores on the surface. The attachment kinetics fit, with high correlation, equations used to describe that adsorption of bacteria to surfaces. This suggests the same physical phenomena drives the attachment of bacteria and swimming algal zoospores to solid surfaces.

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

    Science.gov (United States)

    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

  14. Inhibition of Listeria monocytogenes ATCC 19115 on ham steak by tea bioactive compounds incorporated into chitosan-coated plastic films

    Directory of Open Access Journals (Sweden)

    Vodnar Dan C

    2012-07-01

    Full Text Available Abstract Background The consumer demands for better quality and safety of food products have given rise to the development and implementation of edible films. The use of antimicrobial films can be a promising tool for controlling L. monocytogenes on ready to eat products. The aim of this study was to develop effective antimicrobial films incorporating bioactive compounds from green and black teas into chitosan, for controlling L. monocytogenes ATCC 19115 on vacuum-packaged ham steak. The effectiveness of these antimicrobial films was evaluated at room temperature (20°C for 10 days and at refrigerated temperature (4°C for 8 weeks. Results The HPLC results clearly show that relative concentrations of catechins and caffeine in green tea ranked EGCG>EGC>CAF>ECG>EC>C while in black tea extracts ranked CAF>EGCG>ECG>EGC>EC>C. The chitosan-coated plastic films incorporating green tea and black tea extracts shows specific markers identified by FTIR. Incorporating natural extracts into chitosan showed that the growth of L monocytogenes ATCC 19115 was inhibited. The efficacy of antimicrobial effect of tea extracts incorporated into chitosan-coated plastic film was dose dependent. However, chitosan-coated films without addition of tea extracts did not inhibit the growth of L. monocytogenes ATCC 19115. Chitosan-coated plastic films incorporating 4% Green tea extract was the most effective antimicrobial, reducing the initial counts from 3.2 to 2.65 log CFU/cm2 during room temperature storage and from 3.2 to 1–1.5 log CFU/cm2 during refrigerated storage. Conclusions Incorporation of tea extracts into the chitosan-coated films considerably enhanced their effectiveness against L. monocytogenes ATCC 19115. 4% Green tea incorporated into chitosan-coated plastic film had a better antilisterial effect than 2% green tea or 2% and 4% black tea. Data from this study would provide new formulation options for developing antimicrobial packaging films using tea

  15. Evaluation of cationic micropeptides derived from the innate immune system as inhibitors of marine biofouling.

    Science.gov (United States)

    Trepos, Rozenn; Cervin, Gunnar; Pile, Claire; Pavia, Henrik; Hellio, Claire; Svenson, Johan

    2015-01-01

    A series of 13 short synthetic amphiphilic cationic micropeptides, derived from the antimicrobial iron-binding innate defence protein lactoferrin, have been evaluated for their capacity to inhibit the marine fouling process. The whole biofouling process was studied and microfouling organisms such as marine bacteria and microalgae were included as well as the macrofouling barnacle Balanus improvisus. In total 19 different marine fouling organisms (18 microfoulers and one macrofouler) were included and both the adhesion and growth of the microfoulers were investigated. It was shown that the majority of the peptides inhibited barnacle cyprid settlement via a reversible nontoxic mechanism, with IC50 values as low as 0.5 μg ml(-1). Six peptides inhibited adhesion and growth of microorganisms. Two of these were particularly active against the microfoulers with MIC-values ranging between 0.01 and 1 μg ml(-1), which is comparable with the commercial reference antifoulant SeaNine.

  16. Effect of nitrogen ion implantation on corrosion inhibition of nickel coated 316 stainless steel and correlation with nano-structure

    Science.gov (United States)

    Grayeli-Korpi, Ali-Reza; Savaloni, Hadi

    2012-10-01

    The influence of implantation of N+ with 20 keV energy and different fluences in the range of 1 × 1017 and 5 × 1018 ions/cm2 in the nickel coated type 316 stainless steel (SS) on the corrosion inhibition of SS in 3.5 wt% NaCl solution is investigated. The highest available N+ fluence showed highest corrosion inhibition. X-ray diffraction (XRD) analysis showed formation of nickel nitride phases that enhanced by increasing the N+ fluence. Surface morphology was studied by atomic force microscope (AFM) and scanning electron microscope (SEM) before and after corrosion test, respectively. AFM results showed that by increasing N+ fluence surface of the sample becomes smoother that may be the result of heat accumulation during implantation causing higher rate of diffusion in the sample.

  17. Effects of poly-ether B on proteome and phosphoproteome expression in biofouling Balanus amphitrite cyprids

    KAUST Repository

    Dash, Swagatika

    2012-04-01

    Biofouling is ubiquitous in marine environments, and the barnacle Balanus amphitrite is one of the most recalcitrant and aggressive biofoulers in tropical waters. Several natural antifoulants that were claimed to be non-toxic have been isolated in recent years, although the mechanism by which they inhibit fouling is yet to be investigated. Poly-ether B has shown promise in the non-toxic inhibition of larval barnacle attachment. Hence, in this study, multiplex two-dimensional electrophoresis (2-DE) was applied in conjunction with mass spectrometry to investigate the effects of poly-ether B on barnacle larvae at the molecular level. The cyprid proteome response to poly-ether B treatment was analyzed at the total proteome and phosphoproteome levels, with 65 protein and 19 phosphoprotein spots found to be up- or down-regulated. The proteins were found to be related to energy-metabolism, oxidative stress, and molecular chaperones, thus indicating that poly-ether B may interfere with the redox-regulatory mechanisms governing the settlement of barnacle larvae. The results of this study demonstrate the usefulness of the proteomic technique in revealing the working mechanisms of antifouling compounds. © 2012 Copyright Taylor and Francis Group, LLC.

  18. Processes And Apparatus For Inhibiting Membrane Bio-fouling

    KAUST Repository

    Missimer, Thomas M.

    2012-12-20

    Certain embodiments are directed to a process and apparatus for cleaning and/or regeneration of permeable or semipermeable membranes comprising modulating pressure of a feed stream feeding the permeable or semipermeable membrane and providing intermittent pressure pulses for cleaning and/or regeneration of the permeable or semipermeable membrane.

  19. Data on combination effect of PEG-coated gold nanoparticles and non-thermal plasma inhibit growth of solid tumors.

    Science.gov (United States)

    Kaushik, Nagendra Kumar; Kaushik, Neha; Yoo, Ki Chun; Uddin, Nizam; Kim, Ju Sung; Lee, Su Jae; Choi, Eun Ha

    2016-12-01

    Highly resistant tumor cells are hard to treat at low doses of plasma. Therefore, researchers have gained more attention to development of enhancers for plasma therapy. Some enhancers could improve the efficacy of plasma towards selectivity of cancer cells damage. In this dataset, we report the application of low doses of PEG-coated gold nanoparticles with addition of plasma treatment. This data consists of the effect of PEG-coated GNP and cold plasma on two solid tumor cell lines T98G glioblastoma and A549 lung adenocarcinoma. Cell proliferation, frequency of cancer stem cell population studies by this co-treatment was reported. Finally, we included in this dataset the effect of co-treatment in vivo, using tumor xenograft nude mice models. The data supplied in this article supports the accompanying publication "Low doses of PEG-coated gold nanoparticles sensitize solid tumors to cold plasma by blocking the PI3K/AKT-driven signaling axis to suppress cellular transformation by inhibiting growth and EMT" (N. K. Kaushik, N. Kaushik, K. C. Yoo, N Uddin, J. S. Kim, S. J. Lee et al., 2016) [1]. PMID:27668278

  20. Corrosion Inhibition on SAE 1010 Steel by Nanoscale Exopolysaccharides Coatings Determined by Electrochemical and Surface Characterization

    Science.gov (United States)

    Plating, painting and the application of enamel are the most common anti-corrosion treatments. They are effective by providing a barrier of corrosion resistant material between the damaging environment and the structural material. Coatings start failing rapidly if scratched or damaged because a co...

  1. PROBLEMS OF BIOFOULING ON FISH–CAGE NETS IN AQUACULTURE

    Directory of Open Access Journals (Sweden)

    Merica Slišković

    2002-09-01

    Full Text Available Biofouling on fish–cage netting is a serious technical and economical problem to aquaculture worldwide. Compensation for the effects of biofouling must be included in cage system design and planning, as fouling can dramatically increase both weight and drag. Settlements of sessile plants and animals, with accumulation of the detritus diminish the size of mesh and can rapidly occlude mesh. Negative effect of smaller mesh size is changing in water flow trough the cages. Biofouling problems necessitating purchase of a second sets of nets or more, and frequent cleaning and changing of biofouling. Changing and cleaning frequency depend on many factors such as: location of cages (near the coast or off shore, productivity of that location, time of the year, time period in which the cages are placed on that location (cause of loading of phosphorus and nitrogen from the unconsumed food in the sediment. Net changing and cleaning procedures are labor and capital intensive. Process of the cleaning of the nets is inadequate, especially when there isnžt adequate equipment available as it is case in smaller aquaculture industry. Chemical control of biofouling e. g. use of antifoulants is questioningly cause of their possible negative effects on breeding species and environment.

  2. Biofouling behavior and performance of forward osmosis membranes with bioinspired surface modification in osmotic membrane bioreactor.

    Science.gov (United States)

    Li, Fang; Cheng, Qianxun; Tian, Qing; Yang, Bo; Chen, Qianyuan

    2016-07-01

    Forward osmosis (FO) has received considerable interest for water and energy related applications in recent years. Biofouling behavior and performance of cellulose triacetate (CTA) forward osmosis membranes with bioinspired surface modification via polydopamine (PD) coating and poly (ethylene glycol) (PEG) grafting (PD-g-PEG) in a submerged osmotic membrane bioreactor (OMBR) were investigated in this work. The modified membranes exhibited lower flux decline than the pristine one in OMBR, confirming that the bioinspired surface modification improved the antifouling ability of the CTA FO membrane. The result showed that the decline of membrane flux related to the increase of the salinity and MLSS concentration of the mixed liquid. It was concluded that the antifouling ability of modified membranes ascribed to the change of surface morphology in addition to the improvement of membrane hydrophilicity. The bioinspired surface modifications might improve the anti-adhesion for the biopolymers and biocake.

  3. The antibacterial and anti-biofouling performance of biogenic silver nanoparticles by Lactobacillus fermentum.

    Science.gov (United States)

    Zhang, Manying; Zhang, Kaisong; De Gusseme, Bart; Verstraete, Willy; Field, Robert

    2014-01-01

    Biofouling is a major challenge in the water industry and public health. Silver nanoparticles (AgNPs) have excellent antimicrobial properties and are considered to be a promising anti-biofouling agent. A modified method was used to produce small sized and well-dispersed biogenic silver nanoparticles with a mean size of ~6 nm (Bio-Ag0-6) using Lactobacillus fermentum. The morphology, size distribution, zeta potential and oxidation state of the silver were systematically characterized. Determination of minimal inhibitory and bactericidal concentration results revealed that biogenic silver Bio-Ag(0-6) can effectively suppress the growth of the test bacteria. Additionally, the inhibition effects of Bio-Ag(0-6) on biofilm formation and on established biofilms were evaluated using P. aeruginosa (ATCC 27853) as the model bacterium. The results from microtiter plates and confocal laser scanning microscopy demonstrated that Bio-Ag(0-6) not only exhibited excellent antibacterial performance but also could control biofilm formation and induce detachment of the bulk of P. aeruginosa biofilms leaving a small residual matrix.

  4. Study on interactions between suspended matter and biofouling formed by treated sewage.

    Science.gov (United States)

    Yang, Qianpeng; Chang, Siyuan; Shi, Lin

    2015-01-01

    Heat exchangers used for treated sewage energy recovery usually suffer from the composite fouling problem, which seriously impairs the heat transfer efficiency. Treated sewage heat exchanger composite fouling is mostly composed of biofouling and is notably affected by interactions between the biofouling and suspended matter. Experiments were performed using simulated treated sewage and two kinds of simulated suspended matter, silicon dioxide particles and polyamide filaments, to model the interactions. Different flow velocities, particle sizes and concentrations were tested with their influences presented by the fouling wet weight changes. Empirical equation and threshold were developed based on the results to predict whether the suspended matter promotes or impedes fouling growth. The results indicate that proper control of the flow velocities, particle sizes and concentrations of suspended matter using empirical equation and threshold can inhibit fouling by reducing unwanted positive interactions and promoting beneficial negative interactions. The filament interactions were analysed and the unique attachment mechanisms of filaments were discussed for the first time. PMID:25950118

  5. Tyrosine- and tryptophan-coated gold nanoparticles inhibit amyloid aggregation of insulin.

    Science.gov (United States)

    Dubey, Kriti; Anand, Bibin G; Badhwar, Rahul; Bagler, Ganesh; Navya, P N; Daima, Hemant Kumar; Kar, Karunakar

    2015-12-01

    Here, we have strategically synthesized stable gold (AuNPs(Tyr), AuNPs(Trp)) and silver (AgNPs(Tyr)) nanoparticles which are surface functionalized with either tyrosine or tryptophan residues and have examined their potential to inhibit amyloid aggregation of insulin. Inhibition of both spontaneous and seed-induced aggregation of insulin was observed in the presence of AuNPs(Tyr), AgNPs(Tyr), and AuNPs(Trp) nanoparticles. These nanoparticles also triggered the disassembly of insulin amyloid fibrils. Surface functionalization of amino acids appears to be important for the inhibition effect since isolated tryptophan and tyrosine molecules did not prevent insulin aggregation. Bioinformatics analysis predicts involvement of tyrosine in H-bonding interactions mediated by its C=O, -NH2, and aromatic moiety. These results offer significant opportunities for developing nanoparticle-based therapeutics against diseases related to protein aggregation.

  6. Silver-nanoparticle-coated biliary stent inhibits bacterial adhesion in bacterial cholangitis in swine

    Institute of Scientific and Technical Information of China (English)

    Wei Wen; Li-Mei Ma; Wei He; Xiao-Wei Tang; Yin Zhang; Xiang Wang; Li Liu; Zhi-Ning Fan

    2016-01-01

    BACKGROUND: One of the major limitations of biliary stents is the stent occlusion, which is closely related to the over-growth of bacteria. This study aimed to evaluate the feasibility of a novel silver-nanoparticle-coated polyurethane (Ag/PU) stent in bacterial cholangitis model in swine. METHODS: Ag/PU was designed by coating silver nanopar-ticles on polyurethane (PU) stent. Twenty-four healthy pigs with bacterial cholangitis using Ag/PU and PU stents were ran-domly divided into an Ag/PU stent group (n=12) and a PU stent group (n=12), respectively. The stents were inserted by standard endoscopic retrograde cholangiopancreatography. Laboratory assay was performed for white blood cell (WBC) count, alanine aminotransferase (ALT), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) at baseline time, 8 hours, 1, 2, 3, and 7 days after stent placements. The segment of bile duct containing the stent was examined histologically ex vivo. Implanted bili-ary stents were examined by a scan electron microscope. The amount of silver release was also measured in vitro. RESULTS: The number of inflammatory cells and level of ALT, IL-1β and TNF-α were significantly lower in the Ag/PU stent group than in the PU stent group. Hyperplasia of the mucosa was more severe in the PU stent group than in the Ag/PU stent group. In contrast to the biofilm of bacteria on the PU stent, fewer bacteria adhered to the Ag/PU stent. CONCLUSIONS: PU biliary stents modified with silver nanoparticles are able to alleviate the inflammation of pigs with bacterial cholangitis. Silver-nanoparticle-coated stents are resistant to bacterial adhesion.

  7. European coatings conference - Marine coatings. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    This volume contains 13 lectures (manuscripts or powerpoint foils) with the following topics: 1. Impact of containerization on polyurethane and polyurea in marine and protective coatings (Malte Homann); 2. The application of combinatorial/high-throughput methods to the development of marine coatings (Bret Chisholm); 3. Progress and perspectives in the AMBIO (advanced nanostructured surfaces for the control of biofouling) Project (James Callow); 4. Release behaviour due to shear and pull-off of silicone coatings with a thickness gradient (James G. Kohl); 5. New liquid rheology additives for high build marine coatings (Andreas Freytag); 6. Effective corrosion protection with polyaniline, polpyrrole and polythiophene as anticorrosice additives for marine paints (Carlos Aleman); 7. Potential applications of sol gel technology for marine applications (Robert Akid); 8: Performance of biocide-free Antifouling Coatings for leisure boats (Bernd Daehne); 9. Novel biocidefree nanostructured antifouling coatings - can nano do the job? (Corne Rentrop); 10. One component high solids, VOC compliant high durability finish technology (Adrian Andrews); 11. High solid coatings - the hybrid solution (Luca Prezzi); 12. Unique organofunctional silicone resins for environmentally friendly high-performance coatings (Dieter Heldmann); 13. Silicone-alkyd paints for marine applications: from battleship-grey to green (Thomas Easton).

  8. Inhibition of various gram-positive and gram-negative bacteria growth on selenium nanoparticle coated paper towels

    Directory of Open Access Journals (Sweden)

    Wang Q

    2015-04-01

    Full Text Available Qi Wang,1 Philip Larese-Casanova,2 Thomas J Webster3,41Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA, USA; 2Department of Civil and Environmental Engineering, College of Engineering, Northeastern University, Boston, MA, USA; 3Department of Chemical Engineering, College of Engineering, Northeastern University, Boston, MA, USA; 4Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi ArabiaAbstract: There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns.Keywords: selenium nanoparticles, paper towels, antibacterial

  9. Impact of spacer thickness on biofouling in forward osmosis

    KAUST Repository

    Valladares Linares, Rodrigo

    2014-06-01

    Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux. © 2014 Elsevier Ltd.

  10. Impact of spacer thickness on biofouling in forward osmosis.

    Science.gov (United States)

    Valladares Linares, R; Bucs, Sz S; Li, Z; AbuGhdeeb, M; Amy, G; Vrouwenvelder, J S

    2014-06-15

    Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46 mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux. PMID:24726992

  11. Influence of biofouling on pharmaceuticals rejection in NF membrane filtration.

    Science.gov (United States)

    Botton, Sabrina; Verliefde, Arne R D; Quach, Nhut T; Cornelissen, Emile R

    2012-11-15

    The effects of biomass attachment and growth on the surface characteristics and organic micropollutants rejection performance of nanofiltration membranes were investigated in a pilot installation. Biomass growth was induced by dosing of a readily biodegradable carbon source resulting in the formation of a biofouling in the investigated membrane elements. Surface properties and rejection behaviour of a biofouled and virgin membrane were investigated and compared in terms of surface charge, surface energy and hydrophobicity. The last two were accomplished by performing contact angle measurements on fully hydrated membrane surfaces, in order to mimic the operating conditions of a membrane in contact with water. Compared to a virgin membrane, deposition and growth of biofilm did slightly alter the surface charge, which became more negative, and resulted in a higher hydrophilicity of the membrane surface. In addition, the presence of the negatively charged biofilm induced accumulation of positively charged pharmaceuticals within the biomass layer, which probably also hindered back diffusion. This caused a reduction in rejection efficiency of positively charged solutes but did not alter rejection of neutral and negatively charged pharmaceuticals. Pharmaceuticals rejection was found to positively correlate with the specific free energy of interaction between virgin or biofouled membranes and pharmaceuticals dissolved in the water phase. The rejection values obtained with both virgin and biofouled membranes were compared and found in good agreement with the predictions calculated with a solute transport model earlier developed for high pressure filtration processes. PMID:22960036

  12. Impact of spacer thickness on biofouling in forward osmosis.

    Science.gov (United States)

    Valladares Linares, R; Bucs, Sz S; Li, Z; AbuGhdeeb, M; Amy, G; Vrouwenvelder, J S

    2014-06-15

    Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46 mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux.

  13. Role of Reverse Divalent Cation Diffusion in Forward Osmosis Biofouling.

    Science.gov (United States)

    Xie, Ming; Bar-Zeev, Edo; Hashmi, Sara M; Nghiem, Long D; Elimelech, Menachem

    2015-11-17

    We investigated the role of reverse divalent cation diffusion in forward osmosis (FO) biofouling. FO biofouling by Pseudomonas aeruginosa was simulated using pristine and chlorine-treated thin-film composite polyamide membranes with either MgCl2 or CaCl2 draw solution. We related FO biofouling behavior-water flux decline, biofilm architecture, and biofilm composition-to reverse cation diffusion. Experimental results demonstrated that reverse calcium diffusion led to significantly more severe water flux decline in comparison with reverse magnesium permeation. Unlike magnesium, reverse calcium permeation dramatically altered the biofilm architecture and composition, where extracellular polymeric substances (EPS) formed a thicker, denser, and more stable biofilm. We propose that FO biofouling was enhanced by complexation of calcium ions to bacterial EPS. This hypothesis was confirmed by dynamic and static light scattering measurements using extracted bacterial EPS with the addition of either MgCl2 or CaCl2 solution. We observed a dramatic increase in the hydrodynamic radius of bacterial EPS with the addition of CaCl2, but no change was observed after addition of MgCl2. Static light scattering revealed that the radius of gyration of bacterial EPS with addition of CaCl2 was 20 times larger than that with the addition of MgCl2. These observations were further confirmed by transmission electron microscopy imaging, where bacterial EPS in the presence of calcium ions was globular, while that with magnesium ions was rod-shaped.

  14. Microbe-surface interactions in biofouling and biocorrosion processes.

    Science.gov (United States)

    Beech, Iwona B; Sunner, Jan A; Hiraoka, Kenzo

    2005-09-01

    The presence of microorganisms on material surfaces can have a profound effect on materials performance. Surface-associated microbial growth, i.e. a biofilm, is known to instigate biofouling. The presence of biofilms may promote interfacial physico-chemical reactions that are not favored under abiotic conditions. In the case of metallic materials, undesirable changes in material properties due to a biofilm (or a biofouling layer) are referred to as biocorrosion or microbially influenced corrosion (MIC). Biofouling and biocorrosion occur in aquatic and terrestrial habitats varying in nutrient content, temperature, pressure and pH. Interfacial chemistry in such systems reflects a wide variety of physiological activities carried out by diverse microbial populations thriving within biofilms. Biocorrosion can be viewed as a consequence of coupled biological and abiotic electron-transfer reactions, i.e. redox reactions of metals, enabled by microbial ecology. Microbially produced extracellular polymeric substances (EPS), which comprise different macromolecules, mediate initial cell adhesion to the material surface and constitute a biofilm matrix. Despite their unquestionable importance in biofilm development, the extent to which EPS contribute to biocorrosion is not well-understood. This review offers a current perspective on material/microbe interactions pertinent to biocorrosion and biofouling, with EPS as a focal point, while emphasizing the role atomic force spectroscopy and mass spectrometry techniques can play in elucidating such interactions.

  15. Role of Reverse Divalent Cation Diffusion in Forward Osmosis Biofouling.

    Science.gov (United States)

    Xie, Ming; Bar-Zeev, Edo; Hashmi, Sara M; Nghiem, Long D; Elimelech, Menachem

    2015-11-17

    We investigated the role of reverse divalent cation diffusion in forward osmosis (FO) biofouling. FO biofouling by Pseudomonas aeruginosa was simulated using pristine and chlorine-treated thin-film composite polyamide membranes with either MgCl2 or CaCl2 draw solution. We related FO biofouling behavior-water flux decline, biofilm architecture, and biofilm composition-to reverse cation diffusion. Experimental results demonstrated that reverse calcium diffusion led to significantly more severe water flux decline in comparison with reverse magnesium permeation. Unlike magnesium, reverse calcium permeation dramatically altered the biofilm architecture and composition, where extracellular polymeric substances (EPS) formed a thicker, denser, and more stable biofilm. We propose that FO biofouling was enhanced by complexation of calcium ions to bacterial EPS. This hypothesis was confirmed by dynamic and static light scattering measurements using extracted bacterial EPS with the addition of either MgCl2 or CaCl2 solution. We observed a dramatic increase in the hydrodynamic radius of bacterial EPS with the addition of CaCl2, but no change was observed after addition of MgCl2. Static light scattering revealed that the radius of gyration of bacterial EPS with addition of CaCl2 was 20 times larger than that with the addition of MgCl2. These observations were further confirmed by transmission electron microscopy imaging, where bacterial EPS in the presence of calcium ions was globular, while that with magnesium ions was rod-shaped. PMID:26503882

  16. Inhibition of RNA silencing by the coat protein of Pelargonium flower break virus: distinctions from closely related suppressors.

    Science.gov (United States)

    Martínez-Turiño, Sandra; Hernández, Carmen

    2009-02-01

    Viral-derived double-stranded RNAs (dsRNAs) activate RNA silencing, generating small interfering RNAs (siRNAs) which are incorporated into an RNA-induced silencing complex (RISC) that promotes homology-dependent degradation of cognate RNAs. To counteract this, plant viruses express RNA silencing suppressors. Here, we show that the coat protein (CP) of Pelargonium flower break virus (PFBV), a member of the genus Carmovirus, is able to efficiently inhibit RNA silencing. Interestingly, PFBV CP blocked both sense RNA- and dsRNA-triggered RNA silencing and did not preclude generation of siRNAs, which is in contrast with the abilities that have been reported for other carmoviral CPs. We have also found that PFBV CP can bind siRNAs and that this ability correlates with silencing suppression activity and enhancement of potato virus X pathogenicity. Collectively, the results indicate that PFBV CP inhibits RNA silencing by sequestering siRNAs and preventing their incorporation into a RISC, thus behaving similarly to unrelated viral suppressors but dissimilarly to orthologous ones.

  17. Early non-destructive biofouling detection and spatial distribution: Application of oxygen sensing optodes

    KAUST Repository

    Farhat, N.M.

    2015-06-11

    Biofouling is a serious problem in reverse osmosis/nanofiltration (RO/NF) applications, reducing membrane performance. Early detection of biofouling plays an essential role in an adequate anti-biofouling strategy. Presently, fouling of membrane filtration systems is mainly determined by measuring changes in pressure drop, which is not exclusively linked to biofouling. Non-destructive imaging of oxygen concentrations (i) is specific for biological activity of biofilms and (ii) may enable earlier detection of biofilm accumulation than pressure drop. The objective of this study was to test whether transparent luminescent planar O2 optodes, in combination with a simple imaging system, can be used for early non-destructive biofouling detection. This biofouling detection is done by mapping the two-dimensional distribution of O2 concentrations and O2 decrease rates inside a membrane fouling simulator (MFS). Results show that at an early stage, biofouling development was detected by the oxygen sensing optodes while no significant increase in pressure drop was yet observed. Additionally, optodes could detect spatial heterogeneities in biofouling distribution at a micro scale. Biofilm development started mainly at the feed spacer crossings. The spatial and quantitative information on biological activity will lead to better understanding of the biofouling processes, contributing to the development of more effective biofouling control strategies.

  18. Early non-destructive biofouling detection and spatial distribution: Application of oxygen sensing optodes.

    Science.gov (United States)

    Farhat, N M; Staal, M; Siddiqui, A; Borisov, S M; Bucs, Sz S; Vrouwenvelder, J S

    2015-10-15

    Biofouling is a serious problem in reverse osmosis/nanofiltration (RO/NF) applications, reducing membrane performance. Early detection of biofouling plays an essential role in an adequate anti-biofouling strategy. Presently, fouling of membrane filtration systems is mainly determined by measuring changes in pressure drop, which is not exclusively linked to biofouling. Non-destructive imaging of oxygen concentrations (i) is specific for biological activity of biofilms and (ii) may enable earlier detection of biofilm accumulation than pressure drop. The objective of this study was to test whether transparent luminescent planar O2 optodes, in combination with a simple imaging system, can be used for early non-destructive biofouling detection. This biofouling detection is done by mapping the two-dimensional distribution of O2 concentrations and O2 decrease rates inside a membrane fouling simulator (MFS). Results show that at an early stage, biofouling development was detected by the oxygen sensing optodes while no significant increase in pressure drop was yet observed. Additionally, optodes could detect spatial heterogeneities in biofouling distribution at a micro scale. Biofilm development started mainly at the feed spacer crossings. The spatial and quantitative information on biological activity will lead to better understanding of the biofouling processes, contributing to the development of more effective biofouling control strategies.

  19. Inhibition of lanthanide nanocrystal-induced inflammasome activation in macrophages by a surface coating peptide through abrogation of ROS production and TRPM2-mediated Ca(2+) influx.

    Science.gov (United States)

    Yao, Han; Zhang, Yunjiao; Liu, Liu; Xu, Youcui; Liu, Xi; Lin, Jun; Zhou, Wei; Wei, Pengfei; Jin, Peipei; Wen, Long-Ping

    2016-11-01

    Lanthanide-based nanoparticles (LNs) hold great promise in medicine. A variety of nanocrystals, including LNs, elicits potent inflammatory response through activation of NLRP3 inflammasome. We have previously identified an LNs-specific surface coating peptide RE-1, with the sequence of 'ACTARSPWICG', which reduced nanocrystal-cell interaction and abrogated LNs-induced autophagy and toxicity in both HeLa cells and liver hepatocytes. Here we show that RE-1 coating effectively inhibited LNs-induced inflammasome activation, mostly mediated by NLRP3, in mouse bone marrow derived macrophage (BMDM) cells, human THP-1 cells and mouse peritoneal macrophages and also reduced LNs-elicited inflammatory response in vivo. RE-1 coating had no effect on cellular internalization of LNs in BMDM cells, in contrast to the situation in HeLa cells where cell uptake of LNs was significantly inhibited by RE-1. To elucidate the molecular mechanism underlying the inflammasome-inhibiting effect of RE-1, we assessed several parameters known to influence nanocrystal-induced NLRP3 inflammasome activation. RE-1 coating did not reduce potassium efflux, which occurred after LNs treatment in BMDM cells and was necessary but insufficient for LNs-induced inflammasome activation. RE-1 did decrease lysosomal damage induced by LNs, but the inhibitor of cathepsin B did not affect LNs-elicited caspase 1 activation and IL-1β release, suggesting that lysosomal damage was not critically important for LNs-induced inflammasome activation. On the other hand, LNs-induced elevation of intracellular reactive oxygen species (ROS), critically important for inflammasome activation, was largely abolished by RE-1 coating, with the reduction on NADPH oxidase-generated ROS playing a more prominent role for RE-1's inflammasome-inhibiting effect than the reduction on mitochondria-generated ROS. ROS generation further triggered Ca(2+) influx, an event that was mediated by Transient Receptor Potential M2 (TRPM2) and was

  20. Application of a novel antimicrobial coating on roast beef for inactivation and inhibition of Listeria monocytogenes during storage.

    Science.gov (United States)

    Wang, Luxin; Zhao, Liang; Yuan, Jing; Jin, Tony Z

    2015-10-15

    The antilisterial efficacy of novel coating solutions made with organic acids, lauric arginate ester, and chitosan was evaluated in a three-stage study on inoculated roast beef for the first time. Ready-to-eat roast beef was specially ordered from the manufacturer. The meat surface was inoculated with five-strain Listeria monocytogenes cocktail inoculums at two different levels, ~3 and 6 Log CFU/cm(2) and treated with the stock solution (HAMS), the 1:5 diluted solution (MAMS), and the 1:10 diluted solution (LAMS) (stage 1). During the 20 min contact time, the antimicrobial coatings reduced the Listeria populations by approximately 0.9-0.3 Log CFU/cm(2). The higher the concentrations of the antimicrobial solution, the better the antilisterial effects were. The treated inoculated beef samples were then stored at 4 °C for 30 days. During storage, Listeria growth inhibition effects were seen. While no growth was seen from the HAMS-treated samples, a 1.6 Log CFU/cm(2) increase was seen for MAMS-treated samples, a 4.6 Log CFU/cm(2) increase was seen for LAMS-treated samples, and a 5.7 Log CFU/cm(2) increase was seen for NoAMS-treated samples on Day 30 (~3 Log CFU/cm(2) inoculation level). In the second stage, the impact of the roast beef storage time on solution's antilisterial effect was evaluated. Results showed that the effect of the antimicrobial solution was dependent on both the initial inoculation levels and storage times. In stage 3, the effect of the antimicrobial solution on roast beef quality was studied with both instrument measurement and sensory evaluation. Minor changes in color, pH, and water activity were found. However, only limited sensory differences were seen between the treated and untreated samples. When panels were able to accurately find color differences between samples, they preferred the treated samples. The findings of this research proved the antilisterial efficacy of the novel antimicrobial solution and showed its potential for being used

  1. Pathogenic Vibrio parahaemolyticus isolated from biofouling on commercial vessels and harbor structures.

    Science.gov (United States)

    Revilla-Castellanos, Valeria J; Guerrero, Abraham; Gomez-Gil, Bruno; Navarro-Barrón, Erick; Lizárraga-Partida, Marcial L

    2015-01-01

    Ballast water is a significant vector of microbial dissemination; however, biofouling on commercial vessel hulls has been poorly studied with regard to pathogenic bacteria transport. Biofouling on three commercial vessels and seven port structures in Ensenada, Baja California, Mexico, was examined by qPCR to identify and quantify Vibrio parahaemolyticus, a worldwide recognized food-borne human pathogen. Pathogenic variants (trh+, tdh+) of V. parahaemolyticus were detected in biofouling homogenates samples from several docks in Ensenada and on the hulls of ships with Japanese and South Korean homeports, but not in reference sampling stations. A total of 26 tdh+ V. parahaemolyticus colonies and 1 ORF8+/O3:K6 strain were also isolated from enriched biofouling homogenate samples confirming the qPCR analysis. Our results suggest that biofouling is an important reservoir of pathogenic vibrios. Thus, ship biofouling might be an overlooked vector with regard to the dissemination of pathogens, primarily pathogenic V. parahaemolyticus.

  2. Effect of chitosan and thiolated chitosan coating on the inhibition behaviour of PIBCA nanoparticles against intestinal metallopeptidases

    International Nuclear Information System (INIS)

    Surface modified nanoparticles composed of poly(isobutylcyanoacrylate) (PIBCA) cores surrounded by a chitosan and thiolated chitosan gel layer were prepared and characterized in previous works. The presence of such biopolymers on the nanoparticle surface conferred those nanosystems interesting characteristics that might partially overcome the gastrointestinal enzymatic barrier, improving the oral administration of pharmacologically active peptides. In the present work, the antiprotease behaviour of this family of core-shell nanoparticles was in vitro tested against two model metallopeptidases present in the gastrointestinal tract (GIT): Carboxypeptidase A -CP A- (luminal protease) and Leucine Aminopeptidase M -LAP M- (membrane protease). As previous step, the zinc-binding capacity of these nanoparticles was evaluated. Interestingly, an improvement of both the zinc-binding capacity and the antiprotease effect of chitosan was observed when the biopolymers (chitosan and thiolated chitosan) were used as coating component of the core-shell nanoparticles, in comparison with their behaviour in solution, thanks to the different biopolymer chains rearrangement. The presence of amino, hydroxyl and thiol groups on the nanoparticle surface promoted zinc binding and hence the inhibition of the metallopeptidases analysed. On the contrary, the occurrence of a cross-linked structure in the gel layer surrounding the PIBCA cores of thiolated formulations, due to the formation of interchain and intrachain disulphide bonds, partially limited the inhibition of the proteases. The low accessibility of cations to the active groups of the cross-linked polymeric shell was postulated as a possible explanation of this behaviour. Results obtained in this work make this family of surface-modified nanocarriers promising candidates for the successfull administration of pharmacologically active peptides and proteins by the oral route.

  3. Microbial speciation and biofouling potential of cooling water used by Ontario Hydro

    International Nuclear Information System (INIS)

    The cooling water composition and microbial components of biofilms attached to stainless steel wafers submerged in three lake water types were evaluated to determine whether their biofouling potential differed in a predictable manner. The composition of the lake waters was different which affected biofilm composition, where the predominance of specific microbial groups varied between test systems and with time. Some prediction of biofouling potential was possible, and it was concluded that the cooling water in the vicinity of Bruce NGS had the lowest biofouling potential whereas greater biofouling could be expected in the Pickering and Nanticoke stations

  4. Antifouling technology-past, present and future steps towards efficient and environmentally friendly antifouling coatings

    DEFF Research Database (Denmark)

    Yebra, Diego Meseguer; Kiil, Søren; Dam-Johansen, Kim

    2004-01-01

    of marine biofouling on ships in an environmentally friendly manner. The main objective of this review is to describe these products in as much detail as possible based on the knowledge available in the open literature. This knowledge has been supplemented by means of performance data provided, upon request...... understanding of the biological principles of the biofouling process is also considered in this review. From the analysis of the factors affecting the biofouling process, the interference with the settlement and attachment mechanisms is the most promising environmentally benign option. This can be accomplished...... obstacles that need to be overcome for the success of this research are analysed. The potential development of broad-spectrum efficient coatings based on natural antifoulants is far from commercialisation. However, exploitation of a weakening of biofouling adhesion by means of the non-stick and fouling...

  5. Fuel efficiency and fouling control coatings in maritime transport

    DEFF Research Database (Denmark)

    Lindholdt, Asger

    First, this thesis concerns the drag performance of fouling control coatings (FCCs) used to protect hulls on ships against biofouling and, therefore, minimize any drag therefrom. A systematic overview of the literature and description of the experimental methods used to quantify the drag of FCCs...

  6. Use of rhamnolipid biosurfactant for membrane biofouling prevention and cleaning.

    Science.gov (United States)

    Kim, Lan Hee; Jung, Yongmoon; Kim, Sung-Jo; Kim, Chang-Min; Yu, Hye-Weon; Park, Hee-Deung; Kim, In S

    2015-01-01

    Rhamnolipids were evaluated as biofouling reducing agents in this study. The permeability of the bacterial outer membrane was increased by rhamnolipids while the growth rate of Pseudomonas aeruginosa was not affected. The surface hydrophobicity was increased through the release of lipopolysaccharides and extracellular polymeric substances from the outer cell membrane. Rhamnolipids were evaluated as agents for the prevention and cleaning of biofilms. A high degree of biofilm detachment was observed when the rhamnolipids were used as a cleaning agent. In addition, effective biofilm reduction occurred when rhamnolipids were applied to various species of Gram-negative bacteria isolated from seawater samples. Biofilm reduction using rhamnolipids was comparable to commercially available surfactants. In addition, 20% of the water flux was increased after rhamnolipid treatment (300 μg ml(-1), 6 h exposure time) in a dead-end filtration system. Rhamnolipids appear to have promise as biological agents for reducing membrane biofouling.

  7. Validation of 3D simulations of reverse osmosis membrane biofouling.

    Science.gov (United States)

    Pintelon, Thomas R R; Creber, Sarah A; von der Schulenburg, Daniel A Graf; Johns, Michael L

    2010-07-01

    The increasing demand for drinking water and its stricter quality requirements have resulted in an exponentially expanding industry of membrane filtration processes. Currently, reverse osmosis (RO) is the most common method of desalination, able to produce water that is virtually free of pollutants and pathogenic micro-organisms. Biofouling of these devices however is a significant limitation. Here we present a 3D simulation of RO membrane biofouling based on a lattice Boltzmann (LB) platform that we subsequently favorably compare with experimental data. This data consists of temporally (and spatially) resolved velocity measurements acquired for a RO membrane using magnetic resonance techniques. The effect of biofilm cohesive strength on system pressure drop is then explored; weaker biomass is observed to have a reduced impact on pressure drop (per unit biomass accumulated).

  8. The biofilm ecology of microbial biofouling, biocide resistance and corrosion

    Energy Technology Data Exchange (ETDEWEB)

    White, D.C. [Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology]|[Oak Ridge National Lab., TN (United States). Environmental Science Div.; Kirkegaard, R.D.; Palmer, R.J. Jr.; Flemming, C.A.; Chen, G.; Leung, K.T.; Phiefer, C.B. [Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology; Arrage, A.A. [Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology]|[Microbial Insights, Inc., Rockford, TN (United States)

    1997-06-01

    In biotechnological or bioremediation processes it is often the aim to promote biofilm formation, and maintain active, high density biomass. In other situations, biofouling can seriously restrict effective heat transport, membrane processes, and potentate macrofouling with loss of transportation efficiency. In biotechnological or bioremediation processes it is often the aim to promote biofilm formation, and maintain active, high density biomass. In other situations, biofouling can seriously restrict effective heat transport, membrane processes, and potentate macrofouling with loss of transportation efficiency. Heterogeneous distribution of microbes and/or their metabolic activity can promote microbially influenced corrosion (MIC) which is a multibillion dollar problem. Consequently, it is important that biofilm microbial ecology be understood so it can be manipulated rationally. It is usually simple to select organisms that form biofilms by flowing a considerably dilute media over a substratum, and propagating the organisms that attach. To examine the biofilm most expeditiously, the biomass accumulation, desquamation, and metabolic activities need to be monitored on-line and non-destructively. This on-line monitoring becomes even more valuable if the activities can be locally mapped in time and space within the biofilm. Herein the authors describe quantitative measures of microbial biofouling, the ecology of pathogens in drinking water distributions systems, and localization of microbial biofilms and activities with localized MIC.

  9. Does chlorination of seawater reverse osmosis membranes control biofouling?

    Science.gov (United States)

    Khan, Muhammad Tariq; Hong, Pei-Ying; Nada, Nabil; Croue, Jean Philippe

    2015-07-01

    Biofouling is the major problem of reverse osmosis (RO) membranes used for desalting seawater (SW). The use of chlorine is a conventional and common practice to control/prevent biofouling. Unlike polyamide RO membranes, cellulose triacetate (CTA) RO membranes display a high chlorine tolerance. Due to this characteristic, CTA membranes are used in most of the RO plants located in the Middle East region where the elevated seawater temperature and water quality promote the risk of membrane biofouling. However, there is no detailed study on the investigation/characterization of CTA-RO membrane fouling. In this investigation, the fouling profile of a full-scale SWRO desalination plant operating with not only continuous chlorination of raw seawater but also intermittent chlorination of CTA-RO membranes was studied. Detailed water quality and membrane fouling analyses were conducted. Profiles of microbiological, inorganic, and organic constituents of analysed fouling layers were extensively discussed. Our results clearly identified biofilm development on these membranes. The incapability of chlorination on preventing biofilm formation on SWRO membranes could be assigned to its failure in effectively reaching throughout the different regions of the permeators. This failure could have occurred due to three main factors: plugging of membrane fibers, chlorine consumption by organics accumulated on the front side fibers, or chlorine adaptation of certain bacterial populations. PMID:25917390

  10. Does Chlorination of Seawater Reverse Osmosis Membranes Control Biofouling?

    KAUST Repository

    Khan, Muhammad Tariq

    2015-04-01

    Biofouling is the major problem of reverse osmosis (RO) membranes used for desalting seawater (SW). The use of chlorine is a conventional and common practice to control/prevent biofouling. Unlike polyamide RO membranes, cellulose triacetate (CTA) RO membranes display a high chlorine tolerance. Due to this characteristic, CTA membranes are used in most of the RO plants located in the Middle East region where the elevated seawater temperature and water quality promote the risk of membrane biofouling. However, there is no detailed study on the investigation/characterization of CTA-RO membrane fouling. In this investigation, the fouling profile of a full–scale SWRO desalination plant operating with not only continuous chlorination of raw seawater but also intermittent chlorination of CTA-RO membranes was studied. Detailed water quality and membrane fouling analyses were conducted. Profiles of microbiological, inorganic, and organic constituents of analysed fouling layers were extensively discussed. Our results clearly identified biofilm development on these membranes. The incapability of chlorination on preventing biofilm formation on SWRO membranes could be assigned to its failure in effectively reaching throughout the different regions of the permeators. This failure could have occurred due to three main factors: plugging of membrane fibers, chlorine consumption by organics accumulated on the front side fibers, or chlorine adaptation of certain bacterial populations.

  11. Does chlorination of seawater reverse osmosis membranes control biofouling?

    Science.gov (United States)

    Khan, Muhammad Tariq; Hong, Pei-Ying; Nada, Nabil; Croue, Jean Philippe

    2015-07-01

    Biofouling is the major problem of reverse osmosis (RO) membranes used for desalting seawater (SW). The use of chlorine is a conventional and common practice to control/prevent biofouling. Unlike polyamide RO membranes, cellulose triacetate (CTA) RO membranes display a high chlorine tolerance. Due to this characteristic, CTA membranes are used in most of the RO plants located in the Middle East region where the elevated seawater temperature and water quality promote the risk of membrane biofouling. However, there is no detailed study on the investigation/characterization of CTA-RO membrane fouling. In this investigation, the fouling profile of a full-scale SWRO desalination plant operating with not only continuous chlorination of raw seawater but also intermittent chlorination of CTA-RO membranes was studied. Detailed water quality and membrane fouling analyses were conducted. Profiles of microbiological, inorganic, and organic constituents of analysed fouling layers were extensively discussed. Our results clearly identified biofilm development on these membranes. The incapability of chlorination on preventing biofilm formation on SWRO membranes could be assigned to its failure in effectively reaching throughout the different regions of the permeators. This failure could have occurred due to three main factors: plugging of membrane fibers, chlorine consumption by organics accumulated on the front side fibers, or chlorine adaptation of certain bacterial populations.

  12. Potential impact of biofouling on the photobioreactors of the Offshore Membrane Enclosures for Growing Algae (OMEGA) system.

    Science.gov (United States)

    Harris, Linden; Tozzi, Sasha; Wiley, Patrick; Young, Colleen; Richardson, Tra-My Justine; Clark, Kit; Trent, Jonathan D

    2013-09-01

    The influence of PBR composition [clear polyurethane (PolyU) vs. clear linear low-density polyethylene (LLDPE) (top) and black opaque high-density polyethylene (bottom)] and shape (rectangular vs. tubular) on biofouling and the influence of biofouling on algae productivity were investigated. In 9-week experiments, PBR biofouling was dominated by pennate diatoms and clear plastics developed macroalgae. LLDPE exhibited lower photosynthetic-active-radiation (PAR) light transmittance than PolyU before biofouling, but higher transmittance afterwards. Both rectangular and tubular LLDPE PBRs accumulated biofouling predominantly along their wetted edges. For a tubular LLDPE PBR after 12 weeks of biofouling, the correlation between biomass, percent surface coverage, and PAR transmittance was complex, but in general biomass inversely correlated with transmittance. Wrapping segments of this biofouled LLDPE around an algae culture reduced CO2 and NH3-N utilization, indicating that external biofouling must be controlled.

  13. Fluorine Based Superhydrophobic Coatings

    Directory of Open Access Journals (Sweden)

    Jean-Denis Brassard

    2012-05-01

    Full Text Available Superhydrophobic coatings, inspired by nature, are an emerging technology. These water repellent coatings can be used as solutions for corrosion, biofouling and even water and air drag reduction applications. In this work, synthesis of monodispersive silica nanoparticles of ~120 nm diameter has been realized via Stöber process and further functionalized using fluoroalkylsilane (FAS-17 molecules to incorporate the fluorinated groups with the silica nanoparticles in an ethanolic solution. The synthesized fluorinated silica nanoparticles have been spin coated on flat aluminum alloy, silicon and glass substrates. Functionalization of silica nanoparticles with fluorinated groups has been confirmed by Fourier Transform Infrared spectroscopy (FTIR by showing the presence of C-F and Si-O-Si bonds. The water contact angles and surface roughness increase with the number of spin-coated thin films layers. The critical size of ~119 nm renders aluminum surface superhydrophobic with three layers of coating using as-prepared nanoparticle suspended solution. On the other hand, seven layers are required for a 50 vol.% diluted solution to achieve superhydrophobicity. In both the cases, water contact angles were more than 150°, contact angle hysteresis was less than 2° having a critical roughness value of ~0.700 µm. The fluorinated silica nanoparticle coated surfaces are also transparent and can be used as paint additives to obtain transparent coatings.

  14. An Investigation of Low Biofouling Copper-charged Membranes

    Science.gov (United States)

    Asapu, Sunitha

    Water is essential for the survival of life on Earth, but pollutants in water can cause dangerous diseases and fatalities. The need for purified water has been increasing with increasing world population; however, natural sources of water such as rivers, lakes and streams, are progressively falling shorter and shorter of meeting water needs. The provision of clean, drinkable water to people is a key factor for the development of novel and alternative water purification technologies, such as membrane separations. Nanofiltration (NF) is a membrane separations technology that purifies water from lower quality sources, such as brackish water, seawater and wastewater. During the filtration of such sources, materials that are rejected by the membrane may accumulate on the surface of the membrane to foul it. Such materials include organic and inorganic matter, colloids, salts and microorganisms. The former four can often be controlled via pretreatment; however, the accumulation of microorganisms is more problematic to membranes. Biofouling is the accumulation and growth of microorganisms on the surface of membranes and on feed spacers. After attachment, microorganisms excrete extracellular polymeric substances (EPS), which form a matrix around the organism's outer surface as biofilm. These biofilms are detrimental and result in irreversible membrane fouling. Copper and silver ions inactivate the bacterial cells and prevent the DNA replication in microbial cells. Previous studies using copper-charged feed spacers have shown the ability of copper to control biofouling without a significant amount of copper leaching from copper-charged polypropylene (PP) feed spacers during crossflow filtration. Also, filtration using unmodified speed facers experienced almost 70% flux decline, while filtration using copper-charged feed spacers displayed only 25% flux decline. These intriguing results led to the hypothesis that the polymer chemistry could be extrapolated to produce membranes

  15. Coral-associated bacteria, quorum sensing disrupters, and the regulation of biofouling.

    Science.gov (United States)

    Golberg, Karina; Pavlov, Valentina; Marks, Robert S; Kushmaro, Ariel

    2013-01-01

    Marine biofouling, the settlement of microorganisms and macroorganisms on structures submerged in seawater, although economically detrimental, is a successful strategy for survival in hostile environments, where coordinated bacterial communities establish biofilms via the regulation of quorum sensing (QS) communication systems. The inhibition of QS activity among bacteria isolated from different coral species was investigated to gain further insight into its potency in the attenuation, or even the prevention, of undesirable biofouling on marine organisms. It is hypothesized that coral mucus/microorganism interactions are competitive, suggesting that the dominant communities secrete QS disruptive compounds. One hundred and twenty bacterial isolates were collected from healthy coral species and screened for their ability to inhibit QS using three bioreporter strains. Approximately 12, 11, and 24% of the isolates exhibited anti-QS activity against Escherichia coli pSB1075, Chromobacterium violaceum CV026, and Agrobacterium tumefaciens KYC55 indicator strains, respectively. Isolates with positive activity against the bioluminescent monitor strains were scanned via a cytotoxic/genotoxic, E. coli TV1061 and DPD2794 antimicrobial panel. Isolates detected by C. violaceum CV026 and A. tumefaciens KYC55 reporter strains were tested for their ability to inhibit the growth of these reporter strains, which were found to be unaffected. Tests of the Favia sp. coral isolate Fav 2-50-7 (>98% similarity to Vibrio harveyi) for its ability to attenuate the formation of biofilm showed extensive inhibitory activity against biofilms of Pseudomonas aeruginosa and Acinetobacter baumannii. To ascertain the stability and general structure of the active compound, cell-free culture supernatants exposed to an increasing temperature gradient or to digestion by proteinase K, were shown to maintain potent QS attenuation and the ability to inhibit the growth of biofilms. Mass spectrometry confirmed

  16. Mini-review: Assessing the drivers of ship biofouling management--aligning industry and biosecurity goals.

    Science.gov (United States)

    Davidson, Ian; Scianni, Christopher; Hewitt, Chad; Everett, Richard; Holm, Eric; Tamburri, Mario; Ruiz, Gregory

    2016-01-01

    Biofouling exerts a frictional and cost penalty on ships and is a direct cause of invasion by marine species. These negative consequences provide a unifying purpose for the maritime industry and biosecurity managers to prevent biofouling accumulation and transfer, but important gaps exist between these sectors. This mini-review examines the approach to assessments of ship biofouling among sectors (industry, biosecurity and marine science) and the implications for existing and emerging management of biofouling. The primary distinctions between industry and biosecurity in assessment of vessels biofouling revolve around the resolution of biological information collected and the specific wetted surface areas of primary concern to each sector. The morphological characteristics of biofouling and their effects on propulsion dynamics are of primary concern to industry, with an almost exclusive focus on the vertical sides and flat bottom of hulls and an emphasis on antifouling and operational performance. In contrast, the identity, biogeography, and ecology of translocated organisms is of highest concern to invasion researchers and biosecurity managers and policymakers, especially as it relates to species with known histories of invasion elsewhere. Current management practices often provide adequate, although not complete, provision for hull surfaces, but niche areas are well known to enhance biosecurity risk. As regulations to prevent invasions emerge in this arena, there is a growing opportunity for industry, biosecurity and academic stakeholders to collaborate and harmonize efforts to assess and manage biofouling of ships that should lead to more comprehensive biofouling solutions that promote industry goals while reducing biosecurity risk and greenhouse gas emissions.

  17. Quantitative biofouling diagnosis in full scale nanofiltration and reverse osmosis installations

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.; Manolarakis, S.A.; Hoek, van der J.P.; Paassen, van J.A.M.; Meer, van der W.G.J.; Agtmaal, van J.M.C.; Prummel, H.D.M.; Kruithof, J.C.; Loosdrecht, M.C.M.

    2008-01-01

    Biofilm accumulation in nanofiltration and reverse osmosis membrane elements results in a relative increase of normalised pressure drop (ΔNPD). However, an increase in ΔNPD is not exclusively linked to biofouling. In order to quantify biofouling, the biomass parameters adenosine triphosphate (ATP),

  18. Experimental investigation of interactions between the temperature field and biofouling in a synthetic treated sewage stream.

    Science.gov (United States)

    Yang, Qianpeng; Wilson, D Ian; Chen, Xiaodong; Shi, Lin

    2013-01-01

    Biofouling causes significant losses in efficiency in heat exchangers recovering waste heat from treated sewage. The influence of the temperature field on biofouling was investigated using a flat plate heat exchanger which simulated the channels in a plate and frame unit. The test surface was a 316 stainless steel plate, and a solution of Bacillus sp. and Aeromonas sp. was used as a model process liquid. The test cell was operated under co-current, counter-current, and constant wall temperature configurations, which gave different temperature distributions. Biofouling was monitored via changes in heat transfer and biofilm thickness. The effect of uniform temperature on biofouling formation was similar to the effect of uniform temperature on planktonic growth of the organisms. Further results showed that the temperature field, and particularly the wall temperature, influenced the rate of biofouling strongly. The importance of wall temperature suggests that fouling could be mitigated by using different configurations in summer and winter.

  19. Self-cleaning Metal Organic Framework (MOF) based ultra filtration membranes--a solution to bio-fouling in membrane separation processes.

    Science.gov (United States)

    Prince, J A; Bhuvana, S; Anbharasi, V; Ayyanar, N; Boodhoo, K V K; Singh, G

    2014-01-01

    Bio-fouling is a serious problem in many membrane-based separation processes for water and wastewater treatment. Current state of the art methods to overcome this are to modify the membranes with either hydrophilic additives or with an antibacterial compound. In this study, we propose and practise a novel concept to prevent bio-fouling by developing a killing and self-cleaning membrane surface incorporating antibacterial silver nanoparticles and highly hydrophilic negatively charged carboxylic and amine functional groups. The innovative surface chemistry helps to reduce the contact angle of the novel membrane by at least a 48% and increase the pure water flux by 39.4% compared to the control membrane. The flux drop for the novel membrane is also lower (16.3% of the initial flux) than the control membrane (55.3% of the initial flux) during the long term experiments with protein solution. Moreover, the novel membrane continues to exhibit inhibition to microbes even after 1320 min of protein filtration. Synthesis of self-cleaning ultrafiltration membrane with long lasting properties opens up a viable solution for bio-fouling in ultrafiltration application for wastewater purification. PMID:25296745

  20. Biocorrosion and biofouling of metals and alloys of industrial usage. present state of the art at the beginning of the new millennium

    Energy Technology Data Exchange (ETDEWEB)

    Videla, H. A.

    2003-07-01

    An overview on the present state of the art on Biocorrosion and Biofouling of metals and alloys of industrial usage is offered on the basis of the experience gathered in our laboratory over 25 years of research. The key concepts to understand the main effects of microorganisms on metal decay are briefly discussed. new trends in monitoring and control strategies to mitigate biocorrosion and biofouling deleterious effects are also described. Several relevant cases of biocorrosion studied by our research group are successively described: i) biocorrosion of aluminum and its alloys by fungal contaminants of jet fuels; ii) Sulfate-reducing bacteria SRB induced corrosion of steel; iii) biocorrosion and biofouling interactions in the marine environment: iv) monitoring strategies for assessing biocorrosion in industrial water systems; v) microbial inhibition of corrosion; vi) use and limitations of electrochemical techniques for evaluating biocorrosion effects. The future perspective of the field is made considering the potential of innovative techniques in microscopy (environmental scanning electron microscopy, confocal scanning laser microscopy, atomic force microscopy), new spectroscopy techniques used for the study of corrosion products and biofilms (energy dispersion X-ray analysis, X-ray photoelectron spectroscopy, electron microprobe analysis) and electrochemistry (electrochemical impedance spectroscopy, electrochemical noise analysis. (Author) 53 refs.

  1. Self-cleaning Metal Organic Framework (MOF) based ultra filtration membranes - A solution to bio-fouling in membrane separation processes

    Science.gov (United States)

    Prince, J. A.; Bhuvana, S.; Anbharasi, V.; Ayyanar, N.; Boodhoo, K. V. K.; Singh, G.

    2014-10-01

    Bio-fouling is a serious problem in many membrane-based separation processes for water and wastewater treatment. Current state of the art methods to overcome this are to modify the membranes with either hydrophilic additives or with an antibacterial compound. In this study, we propose and practise a novel concept to prevent bio-fouling by developing a killing and self-cleaning membrane surface incorporating antibacterial silver nanoparticles and highly hydrophilic negatively charged carboxylic and amine functional groups. The innovative surface chemistry helps to reduce the contact angle of the novel membrane by at least a 48% and increase the pure water flux by 39.4% compared to the control membrane. The flux drop for the novel membrane is also lower (16.3% of the initial flux) than the control membrane (55.3% of the initial flux) during the long term experiments with protein solution. Moreover, the novel membrane continues to exhibit inhibition to microbes even after 1320 min of protein filtration. Synthesis of self-cleaning ultrafiltration membrane with long lasting properties opens up a viable solution for bio-fouling in ultrafiltration application for wastewater purification.

  2. Self-cleaning Metal Organic Framework (MOF) based ultra filtration membranes--a solution to bio-fouling in membrane separation processes.

    Science.gov (United States)

    Prince, J A; Bhuvana, S; Anbharasi, V; Ayyanar, N; Boodhoo, K V K; Singh, G

    2014-01-01

    Bio-fouling is a serious problem in many membrane-based separation processes for water and wastewater treatment. Current state of the art methods to overcome this are to modify the membranes with either hydrophilic additives or with an antibacterial compound. In this study, we propose and practise a novel concept to prevent bio-fouling by developing a killing and self-cleaning membrane surface incorporating antibacterial silver nanoparticles and highly hydrophilic negatively charged carboxylic and amine functional groups. The innovative surface chemistry helps to reduce the contact angle of the novel membrane by at least a 48% and increase the pure water flux by 39.4% compared to the control membrane. The flux drop for the novel membrane is also lower (16.3% of the initial flux) than the control membrane (55.3% of the initial flux) during the long term experiments with protein solution. Moreover, the novel membrane continues to exhibit inhibition to microbes even after 1320 min of protein filtration. Synthesis of self-cleaning ultrafiltration membrane with long lasting properties opens up a viable solution for bio-fouling in ultrafiltration application for wastewater purification.

  3. Thin coatings based on ZnO@C18-usnic acid nanoparticles prepared by MAPLE inhibit the development of Salmonella enterica early biofilm growth

    Science.gov (United States)

    Stan, Miruna Silvia; Constanda, Sabrina; Grumezescu, Valentina; Andronescu, Ecaterina; Ene, Ana Maria; Holban, Alina Maria; Vasile, Bogdan Stefan; Mogoantă, Laurenţiu; Bălşeanu, Tudor-Adrian; Mogoşanu, George Dan; Socol, Gabriel; Grumezescu, Alexandru Mihai; Dinischiotu, Anca; Lazar, Veronica; Chifiriuc, Mariana Carmen

    2016-06-01

    The aim of this study was to develop a nanostructured bioactive surface based on zinc oxide, sodium stearate (C18) and usnic acid (UA) exhibiting harmless effects with respect to the human cells, but with a significant antimicrobial effect, limiting the attachment and biofilm formation of food pathogens. ZnO nanoparticles were synthesized by sol-gel method and functionalized with C18 and UA. The coatings were fabricated by matrix assisted pulsed laser evaporation technique (MAPLE) and further characterized by TEM, SEM, SAED, XRD and IRM. The biological characterization of the prepared coatings consisted in cytotoxicity and antimicrobial assays. The cytotoxicity of ZnO@C18 and ZnO@C18-UA films was evaluated with respect to the human skin fibroblasts (CCD 1070SK cell line) by phase contrast microscopy, MTT assay and nitric oxide (NO) release. The covered surfaces exhibited a decreased cell attachment, effect which was more pronounced in the presence of UA as shown by purple formazan staining of adhered cells. The unattached fibroblasts remained viable after 24 h in the culture media as it was revealed by their morphology analysis and NO level which were similar to uncovered slides. The quantitative microbiological assays results have demonstrated that the bioactive coatings have significantly inhibited the adherence and biofilm formation of Salmonella enterica. The obtained results recommend these materials as efficient approaches in developing anti-adherent coatings for various industrial, medical and food processing applications.

  4. Inhibition of bacterial surface colonization by immobilized silver nanoparticles depends critically on the planktonic bacterial concentration.

    Science.gov (United States)

    Wirth, Stacy M; Bertuccio, Alex J; Cao, Feng; Lowry, Gregory V; Tilton, Robert D

    2016-04-01

    Immobilization of antimicrobial silver nanoparticles (AgNPs) on surfaces has been proposed as a method to inhibit biofouling or as a possible route by which incidental releases of AgNPs may interfere with biofilms in the natural environment or in wastewater treatment. This study addresses the ability of planktonic Pseudomonas fluorescens bacteria to colonize surfaces with pre-adsorbed AgNPs. The ability of the AgNP-coated surfaces to inhibit colonization was controlled by the dissolved silver in the system, with a strong dependence on the initial planktonic cell concentration in the suspension, i.e., a strong inoculum effect. This dependence was attributed to a decrease in dissolved silver ion bioavailability and toxicity caused by its binding to cells and/or cell byproducts. Therefore, when the initial cell concentration was high (∼1×10(7)CFU/mL), an excess of silver binding capacity removed most of the free silver and allowed both planktonic growth and surface colonization directly on the AgNP-coated surface. When the initial cell concentration was low (∼1×10(5)CFU/mL), 100% killing of the planktonic cell inoculum occurred and prevented colonization. When an intermediate initial inoculum concentration (∼1×10(6)CFU/mL) was sufficiently large to prevent 100% killing of planktonic cells, even with 99.97% initial killing, the planktonic population recovered and bacteria colonized the AgNP-coated surface. In some conditions, colonization of AgNP-coated surfaces was enhanced relative to silver-free controls, and the bacteria demonstrated a preferential attachment to AgNP-coated, rather than bare, surface regions. The degree to which the bacterial concentration dictates whether or not surface-immobilized AgNPs can inhibit colonization has significant implications both for the design of antimicrobial surfaces and for the potential environmental impacts of AgNPs. PMID:26771749

  5. Chemical composition influence of cement based mortars on algal biofouling

    Science.gov (United States)

    Estelle, Dalod; Alexandre, Govin; Philippe, Grosseau; Christine, Lors; René, Guyonnet; Denis, Damidot

    2013-04-01

    The main cause of building-facade biodegradation is the growth of microorganisms. This phenomenon depends on several parameters such as the geographical situation, the environmental conditions and the surface state of the substrate. Several researches have been devoted to the study of the effect of porosity and roughness on the biofouling of stones and mortars. However, none of them have addressed the influence of the mortar chemistry on the microorganism growth kinetic. The main objective of this study is to highlight the influence of the mortar chemistry in relationship with its physical properties on biological weathering. Earlier work showed a good resistance of Calcium Aluminate Cements to biodeterioration by acidogenic bacteria (Thiobacillus) and fungi (Alternaria alternata, Aspergillus Niger and Coniosporium uncinatum). In order to characterize the influence of the mortar chemistry on biofouling, two Portland cements and two alumina cements are used. Among micro-organisms able to grow, green algae are most involved in the aesthetic deterioration of facades. Indeed, they can colonize any type of media and can be a source of nutrients for other micro-organisms such as fungi. The green algae Klebsormidium flaccidum is chosen because of its representativeness. It is indeed the species the most frequently identified and isolated from samples taken on sites. The biofouling kinetic is followed on samples exposed outdoor and on samples tested in a laboratory bench which consists in spraying an algae culture on mortar specimens. The results obtained by in situ trials are compared with the results obtained on the laboratory bench. The microorganism growth kinetic is measured by image analysis. To improve the detection of algae on the surface of the cementitious samples, the raw image is converted in the YIQ color space. Y, I and Q correspond respectively to luminance, in-phase, and quadrature. On the Q channel, the areas covered by algae and the areas of clean mortar

  6. Online monitoring of biofouling using coaxial stub resonator technique

    Directory of Open Access Journals (Sweden)

    N.A. Hoog

    2015-03-01

    Analysis of the biofilm and the stub resonator signal, both as function of time, indicates that the sensor allows detection of early stages of biofilm formation. In addition, the sensor signal clearly discriminates between the first stages of biofilm formation (characterized by separated, individual spots of bacterial growth on the glass beads and the presence of a nearly homogeneous biofilm later on in time. Model simulations based on the transmission line theory predict a shift of the sensor response in the same direction and order of magnitude as observed in the biofouling experiments, thereby confirming the operating principle of the sensor.

  7. Marine biofouling in Hong Kong:a review

    Institute of Scientific and Technical Information of China (English)

    Zongguo Huang

    2003-01-01

    From 1980 to 1998, biofouling communities in Hong Kong waters, the Zhujiang RiverEstuary and the Mirs Bay were studied and a total of 610 samples. The samples were collected from ves-sels, buoys, piers and cages. Totally, 340 species (see Appendix Ⅰ ) have been recorded and identified,six of which are new. At the same time, research on the biology of the cirripede, bryozoan, polychaeteand mollusc communities were also conducted. Twenty-three related papers have been published. Thisreview summarizes works in Hong Kong over past twenty years, and some unpublished data are also re-ported.

  8. Improved pharmacokinetics and enhanced tumor growth inhibition using a nanostructured lipid carrier loaded with doxorubicin and modified with a layer-by-layer polyelectrolyte coating.

    Science.gov (United States)

    Mussi, Samuel V; Parekh, Gaurav; Pattekari, Pravin; Levchenko, Tatyana; Lvov, Yuri; Ferreira, Lucas A M; Torchilin, Vladimir P

    2015-11-10

    A nanostructured lipid carrier (NLC) loaded with doxorubicin (DOX) has been shown to be cytotoxic against the human cancer cell lines A549 and MCF-7/Adr. In attempts to improve formulation characteristics, enhance pharmacokinetics and antitumor effects, we modified the surface of these NLC with an alternating layer-by-layer (LbL) assembly of polycation and polyanion polyelectrolytes and an additional coating with PEG using a simple method of core shell attachment. The formulation had a narrow size distribution, longer residence in the blood, lower accumulation in the liver, higher accumulation in tumors and a significant tumor growth inhibition effect. Thus, NLC-DOX nanopreparations complexes modified by LbL coating have the potential to enhance the anticancer effects of DOX against tumors. PMID:26325314

  9. Inactivation of microbial infectiousness by silver nanoparticles-coated condom: a new approach to inhibit HIV- and HSV-transmitted infection

    Directory of Open Access Journals (Sweden)

    Mohammed Fayaz A

    2012-09-01

    anti-HIV activity was primarily mediated by the Ag-NPs, which are associated with the PUC. In addition, the data showed that both macrophage (M-tropic and T lymphocyte (T-tropic strains of HIV-1 were highly sensitive to the Ag-NPs-coated PUC. Furthermore, we also showed that the Ag-NPs-coated PUC was able to inhibit the growth of bacteria and fungi. These results demonstrated that the Ag-NPs-coated PUC is able to directly inactivate the microbe’s infectious ability and provides another defense line against these sexually transmitted microbial infections.Keywords: silver nanoparticles, condom, HIV-1, HSV-1/2, antimicrobial

  10. Diatom attachment inhibition: limiting surface accessibility through air entrapment.

    Science.gov (United States)

    Wu, Alex H-F; Nakanishi, Kenichi; Cho, K L; Lamb, Robert

    2013-12-01

    Surfaces consisting of sub micron holes (0.420-0.765 μm) engineered into nanoparticle (12 nm) coatings were examined for marine antifouling behaviour that defines early stage settlement. Immersed surfaces were found to be resistant to a 5-hour attachment assay of Amphora coffeaeformis, a marine organism commonly found in abundance on fouled substrates such as foul-releasing paints and self-polishing coatings. Attachment inhibition was attributed to the accessibility of diatoms to the surface. This was governed by the size and morphology of trapped interfacial air pockets measured in-situ using synchrotron small angle x-ray scattering. Surfaces containing larger pores (0.765 μm) exhibited the highest resistance. Macroscopic wettability via contact angle measurements however remained at 160° and sliding angle of < 5° and was found to be independent of pore size and not indicative of early stage fouling behaviour. The balance of hierarchical nano/micro length scales was critical in defining the early stage stability of biofouling character of the interface. PMID:24706117

  11. Biofouling of Water Treatment Membranes: A Review of the Underlying Causes, Monitoring Techniques and Control Measures

    Directory of Open Access Journals (Sweden)

    Felicity A. Roddick

    2012-11-01

    Full Text Available Biofouling is a critical issue in membrane water and wastewater treatment as it greatly compromises the efficiency of the treatment processes. It is difficult to control, and significant economic resources have been dedicated to the development of effective biofouling monitoring and control strategies. This paper highlights the underlying causes of membrane biofouling and provides a review on recent developments of potential monitoring and control methods in water and wastewater treatment with the aim of identifying the remaining issues and challenges in this area.

  12. Inhibition of Listeria monocytogenes on cooked cured chicken breasts by acidified coating containing allyl isothiocyanate or deodorized Oriental mustard extract.

    Science.gov (United States)

    Olaimat, Amin N; Holley, Richard A

    2016-08-01

    Ready-to-eat meats are considered foods at high risk to cause life-threatening Listeria monocytogenes infections. This study screened 5 L. monocytogenes strains for their ability to hydrolyze sinigrin (a glucosinolate in Oriental mustard), which formed allyl isothiocyanate (AITC) and reduced L. monocytogenes viability on inoculated vacuum-packed, cooked, cured roast chicken slices at 4 °C. Tests involved incorporation of 25-50 μl/g AITC directly or 100-250 mg/g Oriental mustard extract in 0.5% (w/v) κ-carrageenan/2% (w/v) chitosan-based coatings prepared using 1.5% malic or acetic acid. L. monocytogenes strains hydrolyzed 33.6%-48.4% pure sinigrin in MH broth by 21 d at 25 °C. Acidified κ-carrageenan/chitosan coatings containing 25-50 μl/g AITC or 100-250 mg/g mustard reduced the viability of L. monocytogenes and aerobic bacteria on cooked, cured roast chicken slices by 4.1 to >7.0 log10 CFU/g compared to uncoated chicken stored at 4 °C for 70 d. Coatings containing malic acid were significantly more antimicrobial than those with acetic acid. During storage for 70 d, acidified κ-carrageenan/chitosan coatings containing 25-50 μl/g AITC or 250 mg/g mustard extract reduced lactic acid bacteria (LAB) numbers 3.8 to 5.4 log10 CFU/g on chicken slices compared to uncoated samples. Acidified κ-carrageenan/chitosan-based coatings containing either AITC or Oriental mustard extract at the concentrations tested had the ability to control L. monocytogenes viability and delay growth of potential spoilage bacteria on refrigerated, vacuum-packed cured roast chicken. PMID:27052706

  13. Acetylcholinesterase in Biofouling Species: Characterization and Mode of Action of Cyanobacteria-Derived Antifouling Agents.

    Science.gov (United States)

    Almeida, Joana R; Freitas, Micaela; Cruz, Susana; Leão, Pedro N; Vasconcelos, Vitor; Cunha, Isabel

    2015-07-24

    Effective and ecofriendly antifouling (AF) compounds have been arising from naturally produced chemicals. The objective of this study is to use cyanobacteria-derived agents to investigate the role of acetylcholinesterase (AChE) activity as an effect and/or mode of action of promising AF compounds, since AChE inhibitors were found to inhibit invertebrate larval settlement. To pursue this objective, in vitro quantification of AChE activity under the effect of several cyanobacterial strain extracts as potential AF agents was performed along with in vivo AF (anti-settlement) screening tests. Pre-characterization of different cholinesterases (ChEs) forms present in selected tissues of important biofouling species was performed to confirm the predominance of AChE, and an in vitro AF test using pure AChE activity was developed. Eighteen cyanobacteria strains were tested as source of potential AF and AChE inhibitor agents. Results showed effectiveness in selecting promising eco-friendly AF agents, allowing the understanding of the AF biochemical mode of action induced by different compounds. This study also highlights the potential of cyanobacteria as source of AF agents towards invertebrate macrofouling species.

  14. Nitric Oxide Treatment for the Control of Reverse Osmosis Membrane Biofouling

    OpenAIRE

    Barnes, Robert J.; Low, Jiun Hui; Bandi, Ratnaharika R.; Tay, Martin; Chua, Felicia; Aung, Theingi; Fane, Anthony G.; Kjelleberg, Staffan; Rice, Scott A.

    2015-01-01

    Biofouling remains a key challenge for membrane-based water treatment systems. This study investigated the dispersal potential of the nitric oxide (NO) donor compound, PROLI NONOate, on single- and mixed-species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis (RO) membranes. The potential of PROLI NONOate to control RO membrane biofouling was also examined. Confocal microscopy revealed that PROLI NONOate exposure induced biofilm dispersal in all bu...

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

    OpenAIRE

    Camps, Mercedes; Barani, Aude; Gregori, Gerald; Bouchez, Agnes; 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 copoly...

  16. Rapid novel test for the determination of biofouling potential on reverse osmosis membranes.

    Science.gov (United States)

    Manalo, Cervinia V; Ohno, Masaki; Okuda, Tetsuji; Nakai, Satoshi; Nishijima, Wataru

    2016-01-01

    A novel method was proposed to determine biofouling potential by direct analysis of a reverse osmosis (RO) membrane through fluorescence intensity analysis of biofilm formed on the membrane surface, thereby incorporating fouling tendencies of both feedwater and membrane. Evaluation of the biofouling potential on the RO membrane was done by accelerated biofilm formation through soaking of membranes in high biofouling potential waters obtained by adding microorganisms and glucose in test waters. The biofilm formed on the soaked membrane was quantified by fluorescence intensity microplate analysis. The soaking method's capability in detecting biofilm formation was confirmed when percentage coverage obtained through fluorescence microscopy and intensity values exhibited a linear correlation (R(2) = 0.96). Continuous cross-flow experiments confirmed the ability and reliability of the soaking method in giving biofouling potential on RO membranes when a good correlation (R(2) = 0.87) between intensity values of biofilms formed on the membrane during soaking and filtration conditions was obtained. Applicability of the test developed was shown when three commercially available polyamide (PA) RO membranes were assessed for biofouling potential. This new method can also be applied for the determination of biofouling potential in water with more than 3.6 mg L(-1) easily degradable organic carbon.

  17. Acidification effects on biofouling communities: winners and losers.

    Science.gov (United States)

    Peck, Lloyd S; Clark, Melody S; Power, Deborah; Reis, João; Batista, Frederico M; Harper, Elizabeth M

    2015-05-01

    How ocean acidification affects marine life is a major concern for science and society. However, its impacts on encrusting biofouling communities, that are both the initial colonizers of hard substrata and of great economic importance, are almost unknown. We showed that community composition changed significantly, from 92% spirorbids, 3% ascidians and 4% sponges initially to 47% spirorbids, 23% ascidians and 29% sponges after 100 days in acidified conditions (pH 7.7). In low pH, numbers of the spirorbid Neodexiospira pseudocorrugata were reduced ×5 compared to controls. The two ascidians present behaved differently with Aplidium sp. decreasing ×10 in pH 7.7, whereas Molgula sp. numbers were ×4 higher in low pH than controls. Calcareous sponge (Leucosolenia sp.) numbers increased ×2.5 in pH 7.7 over controls. The diatom and filamentous algal community was also more poorly developed in the low pH treatments compared to controls. Colonization of new surfaces likewise showed large decreases in spirorbid numbers, but numbers of sponges and Molgula sp. increased. Spirorbid losses appeared due to both recruitment failure and loss of existing tubes. Spirorbid tubes are comprised of a loose prismatic fabric of calcite crystals. Loss of tube materials appeared due to changes in the binding matrix and not crystal dissolution, as SEM analyses showed crystal surfaces were not pitted or dissolved in low pH conditions. Biofouling communities face dramatic future changes with reductions in groups with hard exposed exoskeletons and domination by soft-bodied ascidians and sponges.

  18. Inhibition of postharvest penicillium molds of oranges by antifungal hydroxypropyl methylcellulose-lipid edible composite films and coatings

    OpenAIRE

    Silvia A. Valencia-Chamorro; Pérez-Gago, María B.; del Río, Miguel A.; Palou, Lluís

    2010-01-01

    New hydroxypropyl methylcellulose (HPMC)-lipid edible composite films and coatings containing low-toxicity chemicals with antifungal properties were developed. Tested antifungal chemicals were mainly salts of organic acids, salts of parabens, and other compounds, most of them classified as food additives or generally recognized as safe (GRAS) compounds. Stand-alone edible films were used for in vitro evaluation of their antifungal activity against the pathogens Penicillium digitat...

  19. Corrosion and biofouling on the non-heat-exchanger surfaces of an ocean thermal energy conversion power plant: a survey

    Energy Technology Data Exchange (ETDEWEB)

    Castelli, V.J. (ed.)

    1979-05-01

    Of the many foreseeable problems confronting economical ocean thermal energy conversion operation, two major items are the deterioration of the structural and functional components, which prevents efficient operation, and the biofouling of the surfaces, which adds excess weight to the floating ocean platform. The techniques required for effective long-term control of deterioration and corrosion have been investigated actively for many years, and successful solutions for most situations have been developed. For the most part, these solutions can be directly transferred to the ocean thermal energy conversion plant. The majority of problems in these areas are expected to be associated with scale-up and will require some advanced development due to the immensity of the ocean thermal energy conversion platform. Current antifouling control systems are not effective for long-term fouling prevention. Commercially available antifouling coatings are limited to a 3-year service life in temperate waters, and even shorter in tropical waters. However, underwater cleaning techniques and some fouling-control systems presently being used by conventional power plants may find utility on an ocean thermal energy conversion plant. In addition, some recent major advances in long-term antifouling coatings sponsored by the Navy may be applicable to ocean thermal energy conversion. 132 references.

  20. Extract of the seed coat of Tamarindus indica inhibits nitric oxide production by murine macrophages in vitro and in vivo.

    Science.gov (United States)

    Komutarin, T; Azadi, S; Butterworth, L; Keil, D; Chitsomboon, B; Suttajit, M; Meade, B J

    2004-04-01

    The seed coat extract of Tamarindus indica, a polyphenolic flavonoid, has been shown to have antioxidant properties. The present studies investigated the inhibitory effect of the seed coat extract of T. indica on nitric oxide production in vitro using a murine macrophage-like cell line, RAW 264.7, and in vitro and in vivo using freshly isolated B6C3F1 mouse peritoneal macrophages. In vitro exposure of RAW 264.7 cells or peritoneal macrophages to 0.2-200 microg/mL of T. indica extract significantly attenuated (as much as 68%) nitric oxide production induced by lipopolysaccharide (LPS) and interferon gamma (IFN-gamma) in a concentration-dependent manner. In vivo administration of T. indica extract (100-500 mg/kg) to B6C3F1 mice dose-dependently suppressed TPA, LPS and/or IFN-gamma induced production of nitric oxide in isolated mouse peritoneal macrophages in the absence of any effect on body weight. Exposure to T. indica extract had no effect on cell viability as assessed by the MTT assay. In B6C3F1 mice, preliminary safety studies demonstrated a decrease in body weight at only the highest dose tested (1000 mg/kg) without alterations in hematology, serum chemistry or selected organ weights or effects on NK cell activity. A significant decrease in body weight was observed in BALB/c mice exposed to concentrations of extract of 250 mg/kg or higher. Oral exposure of BALB/c mice to T. indica extract did not modulate the development of T cell-mediated sensitization to DNFB or HCA as measured by the local lymph node assay, or dermal irritation to nonanoic acid or DNFB. These studies suggest that in mice, T. indica extract at concentrations up to 500 mg/kg may modulate nitric oxide production in the absence of overt acute toxicity.

  1. Effect of different commercial feed spacers on biofouling of reverse osmosis membrane systems: A numerical study

    KAUST Repository

    Bucs, Szilard

    2014-06-01

    Feed spacers and hydrodynamics have been found relevant for the impact of biofouling on performance in reverse osmosis (RO) and nanofiltration (NF) membrane systems.The objectives of this study on biofouling development were to determine the impact of (i) linear flow velocity and bacterial cell load, (ii) biomass location and (iii) various feed spacer geometries as applied in practice as well as a modified geometry spacer.A three-dimensional mathematical model for biofouling of feed spacer channels including hydrodynamics, solute mass transport and biofilm formation was developed in COMSOL Multiphysics and MATLAB software.Results of this study indicate that the feed channel pressure drop increase caused by biofilm formation can be reduced by using thicker and/or modified feed spacer geometry and/or a lower flow rate in the feed channel. The increase of feed channel pressure drop by biomass accumulation is shown to be strongly influenced by the location of biomass. Results of numerical simulations are in satisfactory agreement with experimental data, indicating that this micro-scale mechanistic model is representative for practice. The developed model can help to understand better the biofouling process of spiral-wound RO and NF membrane systems and to develop strategies to reduce and control biofouling. © 2013 Elsevier B.V.

  2. Transparent exopolymer particles: from aquatic environments and engineered systems to membrane biofouling.

    Science.gov (United States)

    Bar-Zeev, Edo; Passow, Uta; Castrillón, Santiago Romero-Vargas; Elimelech, Menachem

    2015-01-20

    Transparent exopolymer particles (TEP) are ubiquitous in marine and freshwater environments. For the past two decades, the distribution and ecological roles of these polysaccharide microgels in aquatic systems were extensively investigated. More recent studies have implicated TEP as an active agent in biofilm formation and membrane fouling. Since biofouling is one of the main hurdles for efficient operation of membrane-based technologies, there is a heightened interest in understanding the role of TEP in engineered water systems. In this review, we describe relevant TEP terminologies while critically discussing TEP biological origin, biochemical and physical characteristics, and occurrence and distributions in aquatic systems. Moreover, we examine the contribution of TEP to biofouling of various membrane technologies used in the desalination and water/wastewater treatment industry. Emphasis is given to the link between TEP physicochemical and biological properties and the underlying biofouling mechanisms. We highlight that thorough understanding of TEP dynamics in feedwater sources, pretreatment challenges, and biofouling mechanisms will lead to better management of fouling/biofouling in membrane technologies.

  3. Feasibility of supercritical CO₂ treatment for controlling biofouling in the reverse osmosis process.

    Science.gov (United States)

    Mun, Sungmin; Baek, Youngbin; Kim, Cholin; Lee, Youn-Woo; Yoon, Jeyong

    2012-01-01

    Physical cleaning and/or chemical cleaning have been generally used to control biofouling in the reverse osmosis (RO) process. However, conventional membrane cleaning methods to control biofouling are limited due to the generation of by-products and the potential for damage to the RO membranes. In this study, supercritical carbon dioxide (SC CO(2)) treatment, an environmentally friendly technique, was introduced to control biofouling in the RO process. SC CO(2) (100 bar at 35°C) treatment was performed after biofouling was induced on a commercial RO membrane using Pseudomonas aeruginosa PA01 GFP as a model bacterial strain. P. aeruginosa PA01 GFP biofilm cells were reduced on the RO membrane by >8 log within 30 min, and the permeate flux was sufficiently recovered in a laboratory-scale RO membrane system without any significant damage to the RO membrane. These results suggest that SC CO(2) treatment is a promising alternative membrane cleaning technique for biofouling in the RO process.

  4. Slippery liquid-infused porous surface bio-inspired by pitcher plant for marine anti-biofouling application.

    Science.gov (United States)

    Wang, Peng; Zhang, Dun; Lu, Zhou

    2015-12-01

    Marine biofouling, caused by the adhesion of microorganism, is a worldwide problem in marine systems. In this research work, slippery liquid-infused porous surface (SLIPS), inspired by Nepenthes pitcher plant, was constructed over aluminum for marine anti-biofouling application. The as-fabricated SLIPS was characterized with SEM, AFM, and contact angle meter. Its anti-biofouling performance was evaluated with settlement experiment of a typical marine biofouling organism Chlorella vulgaris in both static and dynamic conditions. The effect of solid substrate micro-structure on anti-biofouling property of SLIPS was studied. It was suggested that the micro-structure with low length scale and high degree of regularity should be considered for designing stable SLIPS with exceptional anti-biofouling property. The liquid-like property is proven to be the main contributor for the exceptional anti-biofouling performance of SLIPS in both static and dynamic conditions. The low roughness, which facilitates removing the settled C. vulgaris under shear force, is also a main contributor for the anti-biofouling performance of SLIPS in dynamic condition.

  5. Development and testing of a transparent membrane biofouling monitor

    KAUST Repository

    Dreszer, C.

    2014-01-02

    A modified version of the membrane fouling simulator (MFS) was developed for assessment of (i) hydraulic biofilm resistance, (ii) performance parameters feed-channel pressure drop and transmembrane pressure drop, and (iii) in situ spatial visual and optical observations of the biofilm in the transparent monitor, e.g. using optical coherence tomography. The flow channel height equals the feed spacer thickness enabling operation with and without feed spacer. The effective membrane surface area was enlarged from 80 to 200 cm2 by increasing the monitor width compared to the standard MFS, resulting in larger biomass amounts for analysis. By use of a microfiltration membrane (pore size 0.05 μm) in the monitor salt concentration polarization is avoided, allowing operation at low pressures enabling accurate measurement of the intrinsic hydraulic biofilm resistance. Validation tests on e.g. hydrodynamic behavior, flow field distribution, and reproducibility showed that the small-sized monitor was a representative tool for membranes used in practice under the same operating conditions, such as spiral-wound nanofiltration and reverse osmosis membranes. Monitor studies with and without feed spacer use at a flux of 20 L m-2 h-1 and a cross-flow velocity of 0.1 m s-1 clearly showed the suitability of the monitor to determine hydraulic biofilm resistance and for controlled biofouling studies. © 2013 Balaban Desalination Publications. All rights reserved.

  6. Potential radiation control of biofouling bacteria on intake filters

    Energy Technology Data Exchange (ETDEWEB)

    Eichholz, G.G.; Jones, C.G.; Haynes, H.E.

    1988-01-01

    The biofouling of filters at deep wells supplying water for industrial and drinking water purposes by various iron- and sulfur-reducing bacteria is a wide-spread problem in the United States and can cause serious economic losses. Among the means of control, steam heating or chemical additives can be applied only intermittently and have their own environmental impact. Preliminary studies have shown that installation of a sealed gamma radiation source may provide an alternative solution. Analysis of a range of water samples from contaminated wells identified many of the samples as rich in siderocapsa and pseudomona bacteria. Static and dynamic experiments on water samples at various doses and dose rates have shown that these organisms are relatively radiation-sensitive, with a lethal dose in the range of 200-400Gy (20-40kR). Since the main objective is to restrict growth or deposit of plaque on filters, dose rates of the order of 50-75 Gy/hr would be adequate. Such dose rates could be obtained with relatively weak sources, depending on filter dimensions. A conceptual design for such systems has been proposed.

  7. Potential radiation control of biofouling bacteria on intake filters

    International Nuclear Information System (INIS)

    The biofouling of filters at deep wells supplying water for industrial and drinking water purposes by various iron- and sulfur-reducing bacteria is a wide-spread problem in the United States and can cause serious economic losses. Among the means of control, steam heating or chemical additives can be applied only intermittently and have their own environmental impact. Preliminary studies have shown that installation of a sealed gamma radiation source may provide an alternative solution. Analysis of a range of water samples from contaminated wells identified many of the samples as rich in siderocapsa and pseudomona bacteria. Static and dynamic experiments on water samples at various doses and dose rates have shown that these organisms are relatively radiation-sensitive, with a lethal dose in the range of 200-400Gy (20-40kR). Since the main objective is to restrict growth or deposit of plaque on filters, dose rates of the order of 50-75 Gy/hr would be adequate. Such dose rates could be obtained with relatively weak sources, depending on filter dimensions. A conceptual design for such systems has been proposed. (author)

  8. Functionalised inherently conducting polymers as low biofouling materials.

    Science.gov (United States)

    Zhang, Binbin; Nagle, Alex R; Wallace, Gordon G; Hanks, Timothy W; Molino, Paul J

    2015-01-01

    Diatoms are a major component of microbial biofouling layers that develop on man-made surfaces placed in aquatic environments, resulting in significant economic and environmental impacts. This paper describes surface functionalisation of the inherently conducting polymers (ICPs) polypyrrole (PPy) and polyaniline (PANI) with poly(ethylene glycol) (PEG) and their efficacy as fouling resistant materials. Their ability to resist interactions with the model protein bovine serum albumin (BSA) was tested using a quartz crystal microbalance with dissipation monitoring (QCM-D). The capacity of the ICP-PEG materials to prevent settlement and colonisation of the fouling diatom Amphora coffeaeformis (Cleve) was also assayed. Variations were demonstrated in the dopants used during ICP polymerisation, along with the PEG molecular weight, and the ICP-PEG reaction conditions, all playing a role in guiding the eventual fouling resistant properties of the materials. Optimised ICP-PEG materials resulted in a significant reduction in BSA adsorption, and > 98% reduction in diatom adhesion.

  9. Effect of heparin and alendronate coating on titanium surfaces on inhibition of osteoclast and enhancement of osteoblast function

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Ho-Jin; Yun, Young-Pil [Department of Maxillofacial Biomedical Engineering, School of Dentistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Han, Choong-Wan; Kim, Min Sung [Department of Oral and Maxillofacial Radiology, School of Dentistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Institute of Oral Biology, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kim, Sung Eun; Bae, Min Soo [Department of Maxillofacial Biomedical Engineering, School of Dentistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kim, Gyu-Tae; Choi, Yong-Suk; Hwang, Eui-Hwan [Department of Oral and Maxillofacial Radiology, School of Dentistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Institute of Oral Biology, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Lee, Joon Woo [Department of Technology Commercialization Information, Korea Institute of Science and Technology Information (KISTI), 66, Hoegi-ro, Dongdaemun-gu, Seoul 130-741 (Korea, Republic of); Lee, Jin-Moo; Lee, Chang-Hoon [Department of Oriental Gynecology, College of Oriental Medicine, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kim, Duck-Su [Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kwon, Il Keun, E-mail: kwoni@khu.ac.kr [Department of Maxillofacial Biomedical Engineering, School of Dentistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Institute of Oral Biology, Kyung Hee University, Seoul 130-701 (Korea, Republic of)

    2011-09-23

    Highlights: {yields} We examine bone metabolism of engineered alendronate attached to Ti surfaces. {yields} Alendronate-immobilized Ti enhances activation of osteoblast differentiation. {yields} Alendronate-immobilized Ti inhibits osteoclast differentiation. {yields} Alendronate-immobilized Ti may be a bioactive implant with dual functions. -- Abstract: The failure of orthopedic and dental implants has been attributed mainly to loosening of the implant from host bone, which may be due to weak bonding of the implant material to bone tissue. Titanium (Ti) is used in the field of orthopedic and dental implants because of its excellent biocompatibility and outstanding mechanical properties. Therefore, in the field of materials science and tissue engineering, there has been extensive research to immobilize bioactive molecules on the surface of implant materials in order to provide the implants with improved adhesion to the host bone tissue. In this study, chemically active functional groups were introduced on the surface of Ti by a grafting reaction with heparin and then the Ti was functionalized by immobilizing alendronate onto the heparin-grafted surface. In the MC3T3-E1 cell osteogenic differentiation study, the alendronate-immobilized Ti substrates significantly enhanced alkaline phosphatase activity (ALP) and calcium content. Additionally, nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation of RAW264.7 cells was inhibited with the alendronate-immobilized Ti as confirmed by TRAP analysis. Real time PCR analysis showed that mRNA expressions of osteocalcin and osteopontin, which are markers for osteogenesis, were upregulated in MC3T3-E1 cells cultured on alendronate-immobilized Ti. The mRNA expressions of TRAP and Cathepsin K, markers for osteoclastogenesis, in RAW264.7 cells cultured on alendronate-immobilized Ti were down-regulated. Our study suggests that alendronate-immobilized Ti may be a bioactive implant with dual functions to enhance

  10. Effect of heparin and alendronate coating on titanium surfaces on inhibition of osteoclast and enhancement of osteoblast function

    International Nuclear Information System (INIS)

    Highlights: → We examine bone metabolism of engineered alendronate attached to Ti surfaces. → Alendronate-immobilized Ti enhances activation of osteoblast differentiation. → Alendronate-immobilized Ti inhibits osteoclast differentiation. → Alendronate-immobilized Ti may be a bioactive implant with dual functions. -- Abstract: The failure of orthopedic and dental implants has been attributed mainly to loosening of the implant from host bone, which may be due to weak bonding of the implant material to bone tissue. Titanium (Ti) is used in the field of orthopedic and dental implants because of its excellent biocompatibility and outstanding mechanical properties. Therefore, in the field of materials science and tissue engineering, there has been extensive research to immobilize bioactive molecules on the surface of implant materials in order to provide the implants with improved adhesion to the host bone tissue. In this study, chemically active functional groups were introduced on the surface of Ti by a grafting reaction with heparin and then the Ti was functionalized by immobilizing alendronate onto the heparin-grafted surface. In the MC3T3-E1 cell osteogenic differentiation study, the alendronate-immobilized Ti substrates significantly enhanced alkaline phosphatase activity (ALP) and calcium content. Additionally, nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation of RAW264.7 cells was inhibited with the alendronate-immobilized Ti as confirmed by TRAP analysis. Real time PCR analysis showed that mRNA expressions of osteocalcin and osteopontin, which are markers for osteogenesis, were upregulated in MC3T3-E1 cells cultured on alendronate-immobilized Ti. The mRNA expressions of TRAP and Cathepsin K, markers for osteoclastogenesis, in RAW264.7 cells cultured on alendronate-immobilized Ti were down-regulated. Our study suggests that alendronate-immobilized Ti may be a bioactive implant with dual functions to enhance osteoblast

  11. Monitoring biofouling communities could reduce impacts to mussel aquaculture by allowing synchronisation of husbandry techniques with peaks in settlement.

    Science.gov (United States)

    Sievers, Michael; Dempster, Tim; Fitridge, Isla; Keough, Michael J

    2014-02-01

    Fouling organisms in bivalve aquaculture cause significant economic losses for the industry. Managing biofouling is typically reactive, and involves time- and labour-intensive removal techniques. Mussel spat settlement and biofouling were documented over 20 months at three mussel farms within Port Phillip Bay (PPB), Australia to determine if knowledge of settlement patterns could assist farmers in avoiding biofouling. Mussel spat settlement was largely confined to a 2-month period at one farm. Of the problematic foulers, Ectopleura crocea settlement varied in space and time at all three farms, whilst Ciona intestinalis and Pomatoceros taeniata were present predominantly at one farm and exhibited more distinct settlement periods. Within PPB, complete avoidance of biofouling is impossible. However, diligent monitoring may help farmers avoid peaks in detrimental biofouling species and allow them to implement removal strategies such as manual cleaning, and postpone grading and re-socking practices, until after these peaks.

  12. Green Materials Science and Engineering Reduces Biofouling: Approaches for Medical and Membrane-based Technologies

    Directory of Open Access Journals (Sweden)

    Kerianne M Dobosz

    2015-03-01

    Full Text Available Numerous engineered and natural environments suffer deleterious effects from biofouling and/or biofilm formation. For instance, bacterial contamination on biomedical devices pose serious health concerns. In membrane-based technologies, such as desalination and wastewater reuse, biofouling decreases membrane lifetime and increases the energy required to produce clean water. Traditionally, approaches have combatted bacteria using bactericidal agents. However, due to globalization, a decline in antibiotic discovery, and the widespread resistance of microbes to many commercial antibiotics and metallic nanoparticles, new materials and approaches to reduce biofilm formation are needed. In this mini-review, we cover the recent strategies that have been explored to combat microbial contamination without exerting evolutionary pressure on microorganisms. Renewable feedstocks, relying on structure-property relationships, bioinspired/nature-derived compounds, and green processing methods are discussed. Greener strategies that mitigate biofouling hold great potential to positively impact human health and safety.

  13. Effect of biofouling on the performance of amidoxime-based polymeric uranium adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jiyeon; Gill, Gary A.; Strivens, Jonathan E.; Kuo, Li-Jung; Jeters, Robert T.; Avila, Andrew; Wood, Jordana R.; Schlafer, Nicholas J.; Janke, Christopher J.; Miller, Erin A.; Thomas, Mathew; Addleman, Raymond S.; Bonheyo, George T.

    2016-01-27

    The Marine Science Laboratory at the Pacific Northwest National Laboratory evaluated the impact of biofouling on uranium adsorbent performance. A surface modified polyethylene adsorbent fiber provided by Oak Ridge National Laboratory, AF adsorbent, was tested either in the presence or absence of light to simulate deployment in shallow or deep marine environments. 42-day exposure tests in column and flume settings showed decreased uranium uptake by biofouling. Uranium uptake was reduced by up to 30 %, in the presence of simulated sunlight, which also increased biomass accumulation and altered the microbial community composition on the fibers. These results suggest that deployment below the photic zone would mitigate the effects of biofouling, resulting in greater yields of uranium extracted from seawater.

  14. Spatial variation in biofouling of a unionid mussel (Lampsilis siliquoidea) across the western basin of Lake Erie

    Science.gov (United States)

    Larson, James H.; Evans, Mary; Richardson, William B.; Schaeffer, Jeff; Nelson, John

    2016-01-01

    Invasion of North American waters by nonnative Dreissena polymorpha and D. rostriformis bugensishas resulted in declines of the Unionidae family of native North American mussels. Dreissenid mussels biofoul unionid mussels in large numbers and interfere with unionid movement, their acquisition of food, and the native mussels' ability to open and close their shells. Initial expectations for the Great Lakes included extirpation of unionids where they co-occurred with dreissenids, but recently adult and juvenile unionids have been found alive in several apparent refugia. These unionid populations may persist due to reduced dreissenid biofouling in these areas, and/or due to processes that remove biofoulers. For example locations inaccessible to dreissenid veligers may reduce biofouling and habitats with soft substrates may allow unionids to burrow and thus remove dreissenids. We deployed caged unionid mussels (Lampsilis siliquoidea) at 36 sites across the western basin of Lake Erie to assess spatial variation in biofouling and to identify other areas that might promote the persistence or recovery of native unionid mussels. Biofouling ranged from 0.03 – 26.33 g per mussel, reached a maximum in the immediate vicinity of the mouth of the Maumee River, and appeared to primarily consist of dreissenid mussels. A known mussel refugium in the vicinity of a power plant near the mouth of the Maumee actually exhibited very high biofouling rates, suggesting that low dreissenid colonization did not adequately explain unionid survival in this refugium. In contrast, the southern nearshore area of Lake Erie, near another refugium, had very low biofouling. A large stretch of the western basin appeared to have low biofouling rates and muddy substrates, raising the possibility that these open water areas could support remnant and returning populations of unionid mussels. Previous observations of unionid refugia and the occurrence of low biofouling rates in large areas of the western

  15. Biocorrosion and biofouling of metals and alloys of industrial usage. Present state of the art at the beginning of the new millennium

    Directory of Open Access Journals (Sweden)

    Videla, H. A.

    2003-12-01

    Full Text Available An overview on the present state of the art on Biocorrosion and Biofouling of metals and alloys of industrial usage is offered on the basis of the experience gathered in our laboratory over 25 years of research. The key concepts to understand the main effects of microorganisms on metal decay are briefly discussed. New trends in monitoring and control strategies to mitigate biocorrosion and biofouling deleterious effects are also described. Several relevant cases of biocorrosion studied by our research group are successively described: i biocorrosion of aluminum and its alloys by fungal contaminants of jet fuels; ii Sulfate-reducing bacteria SRB induced corrosion of steel; iii biocorrosion and biofouling interactions in the marine environment; iv monitoring strategies for assessing biocorrosion in industrial water systems; v microbial inhibition of corrosion; vi use and limitations of electrochemical techniques for evaluating biocorrosion effects. The future perspective of the field is made considering the potential of innovative techniques in microscopy (environmental scanning electron microscopy, confocal scanning laser microscopy, atomic force microscopy, new spectroscopical techniques used for the study of corrosion products and biofilms (energy dispersion X-ray analysis, X-ray photoelectron spectroscopy, electron microprobe analysis and electrochemistry (electrochemical impedance spectroscopy, electrochemical noise analysis.

    Se ofrece una revisión del estado actual del conocimiento sobre Biocorrosión y Biofouling de metales y aleaciones de uso industrial basada en la experiencia desarrollada en nuestro laboratorio durante 25 años de investigación en el área. Se discuten brevemente los conceptos clave necesarios para entender los principales efectos de los microorganismos en el deterioro de los metales. También se presentan las nuevas tendencias seguidas para el monitoreo y las nuevas estrategias de control para mitigar

  16. Biofouling and corrosion studies. Final report, Part I, May 1, 1976-December 1977

    Energy Technology Data Exchange (ETDEWEB)

    Mahalingam, L. M.

    1978-01-01

    Three sets of biofouling experiments were conducted. Two of these sets were done in the Pacific Ocean at Keahole Point, Hawaii, and one was in the Caribbean at St. Croix, Virgin Islands. Data and results from these experiments are presented and discussed. Heat transfer, biological, and metallurgical measurements are presented. A brief account of the data analysis procedures, and an assessment of the hardware performance are given. Recommendations are made to improve the quality of the current efforts in the OTEC Biofouling, Corrosion and Materials program.

  17. Pectinatella magnifica (Leidy, 1851) (Bryozoa, Phylactolaemata), a biofouling bryozoan recently introduced to China

    Science.gov (United States)

    Wang, Baoqiang; Wang, Hongzhu; Cui, Yongde

    2016-09-01

    Freshwater biofouling threatens a variety of human activities, from the supply of water and energy to recreation. Several species of freshwater bryozoans are notorious for clogging pipes and filters but have been relatively poorly studied to date. We report, for the first time, a biofouling species of freshwater bryozoan, Pectinatella magnifica (Leidy, 1851), from several freshwater rivers, lakes and ponds in China. A complete description, national distribution and the fouling problems are provided. Exactly how Pectinatella magnifica arrived in China remains unclear, but anthropochory and zoochory are considered to be important dispersal pathways.

  18. Comparison of biofouling mechanisms between cellulose triacetate (CTA) and thin-film composite (TFC) polyamide forward osmosis membranes in osmotic membrane bioreactors.

    Science.gov (United States)

    Wang, Xinhua; Zhao, Yanxiao; Yuan, Bo; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-02-01

    There are two types of popular forward osmosis (FO) membrane materials applied for researches on FO process, cellulose triacetate (CTA) and thin film composite (TFC) polyamide. However, performance and fouling mechanisms of commercial TFC FO membrane in osmotic membrane bioreactors (OMBRs) are still unknown. In current study, its biofouling behaviors in OMBRs were investigated and further compared to the CTA FO membrane. The results indicated that β-D-glucopyranose polysaccharides and microorganisms accounted for approximately 77% of total biovolume on the CTA FO membrane while β-D-glucopyranose polysaccharides (biovolume ratio of 81.1%) were the only dominant biofoulants on the TFC FO membrane. The analyses on the biofouling structure implied that a tighter biofouling layer with a larger biovolume was formed on the CTA FO membrane. The differences in biofouling behaviors including biofoulants composition and biofouling structure between CTA and TFC FO membranes were attributed to different membrane surface properties.

  19. Comparison of biofouling mechanisms between cellulose triacetate (CTA) and thin-film composite (TFC) polyamide forward osmosis membranes in osmotic membrane bioreactors.

    Science.gov (United States)

    Wang, Xinhua; Zhao, Yanxiao; Yuan, Bo; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-02-01

    There are two types of popular forward osmosis (FO) membrane materials applied for researches on FO process, cellulose triacetate (CTA) and thin film composite (TFC) polyamide. However, performance and fouling mechanisms of commercial TFC FO membrane in osmotic membrane bioreactors (OMBRs) are still unknown. In current study, its biofouling behaviors in OMBRs were investigated and further compared to the CTA FO membrane. The results indicated that β-D-glucopyranose polysaccharides and microorganisms accounted for approximately 77% of total biovolume on the CTA FO membrane while β-D-glucopyranose polysaccharides (biovolume ratio of 81.1%) were the only dominant biofoulants on the TFC FO membrane. The analyses on the biofouling structure implied that a tighter biofouling layer with a larger biovolume was formed on the CTA FO membrane. The differences in biofouling behaviors including biofoulants composition and biofouling structure between CTA and TFC FO membranes were attributed to different membrane surface properties. PMID:26700758

  20. On biofouling of microplastic particles of different shapes - some mathematics

    Science.gov (United States)

    Bagaeva, Margarita; Chubarenko, Irina

    2016-04-01

    Transport of microplastic particles in marine environment is difficult to quantify because their physical properties may vary with time. We made an attempt to analyse the behaviour of slightly buoyant particles (e.g., polyethylene, polypropylene), most critical process for which is their fouling: it leads to an increase in the mean particle density and its sinking. Fouling covers the surface of a relatively light particle by a denser growing film; thus, the rate of increase in the total mass is directly proportional to the surface area, and the faster the fouling process is - the sooner the mean particle density reaches the water density; the particle begins sinking, leaves the surface layer with stronger currents and can no longer be transported too far. A simplified model of biofouling in marine environment of a slightly buoyant microplastics (ρp biofouling cover (of density ρb > ρw) increases with time at constant rate, and thus it can be considered as time. Geometrical considerations link surface area of particles of different shapes with time rate of increase in its mass due to fouling up to the water density. Geometrical calculations demonstrate that, for the same mass of plastic material, many small particles have larger surface area than one single large particle, and this way - macroplastics will stay longer at the water surface than microplastics. For spherical particles, the time of fouling up to the water density is directly proportional to the radius of a sphere: τsink ˜ R0/ 3n, where n = R0/ R, i.e., if the particle of radius R0reaches the water density in time τsink, the particle of radius R0/3 requires only τsink/9. Spherical shape has (for the given mass m0) the minimum surface area among all other possible shapes in 3-d space. The calculations performed for the same mass m0 have shown that the ratio of surface areas of a sphere (diameter 5 mm), a film (thickness of 15-30 microns) and a fibre (diameter of 30-100 microns) is about 1 / (50

  1. Mussel-inspired dopamine- and plant-based cardanol-containing polymer coatings for multifunctional filtration membranes.

    Science.gov (United States)

    Choi, Yong-Seok; Kang, Hyo; Kim, Dong-Gyun; Cha, Sang-Ho; Lee, Jong-Chan

    2014-12-10

    A series of copolymers [PCD#s, where # is the weight percentage of dopamine methacrylamide (DMA) in polymers] containing mussel-inspired hydrophilic dopamine and plant-based hydrophobic cardanol moieties was prepared via radical polymerization using DMA and 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) as the monomers. PCD#s were used as coating materials to prevent flux decline of the membranes caused by the adhesion of biofoulants and oil-foulants. Polysulfone (PSf) ultrafiltration membranes coated with PCD#s showed higher biofouling resistance than the bare PSf membrane, and the bactericidal properties of the membranes increased upon increasing the content of HCPM units in the PCD#s. Serendipitously, the PSf membranes coated with the more or less amphiphilic PCD54 and PCD74, having the optimum amount of both hydrophilic DMA and hydrophobic HCPM moieties, showed noticeably higher oil-fouling resistance than the more hydrophilic PCD91-coated membrane, the more hydrophobic PCD0-coated membrane, and the bare PSf membrane. Therefore, multifunctional coating materials having biofouling- and oil-fouling-resistant and bactericidal properties could be prepared from the monomers containing mussel-inspired dopamine and plant-based cardanol groups. PMID:25415754

  2. Development of a setup to enable stable and accurate flow conditions for membrane biofouling studies

    KAUST Repository

    Bucs, Szilárd S.

    2015-07-10

    Systematic laboratory studies on membrane biofouling require experimental conditions that are well defined and representative for practice. Hydrodynamics and flow rate variations affect biofilm formation, morphology, and detachment and impacts on membrane performance parameters such as feed channel pressure drop. There is a suite of available monitors to study biofouling, but systems to operate monitors have not been well designed to achieve an accurate, constant water flow required for a reliable determination of biomass accumulation and feed channel pressure drop increase. Studies were done with membrane fouling simulators operated in parallel with manual and automated flow control, with and without dosage of a biodegradable substrate to the feedwater to enhance biofouling rate. High flow rate variations were observed for the manual water flow system (up to ≈9%) compared to the automatic flow control system (<1%). The flow rate variation in the manual system was strongly increased by biofilm accumulation, while the automatic system maintained an accurate and constant water flow in the monitor. The flow rate influences the biofilm accumulation and the impact of accumulated biofilm on membrane performance. The effect of the same amount of accumulated biomass on the pressure drop increase was related to the linear flow velocity. Stable and accurate feedwater flow rates are essential for biofouling studies in well-defined conditions in membrane systems. © 2015 Balaban Desalination Publications. All rights reserved.

  3. The impact and control of biofouling in marine aquaculture: a review.

    Science.gov (United States)

    Fitridge, Isla; Dempster, Tim; Guenther, Jana; de Nys, Rocky

    2012-01-01

    Biofouling in marine aquaculture is a specific problem where both the target culture species and/or infrastructure are exposed to a diverse array of fouling organisms, with significant production impacts. In shellfish aquaculture the key impact is the direct fouling of stock causing physical damage, mechanical interference, biological competition and environmental modification, while infrastructure is also impacted. In contrast, the key impact in finfish aquaculture is the fouling of infrastructure which restricts water exchange, increases disease risk and causes deformation of cages and structures. Consequently, the economic costs associated with biofouling control are substantial. Conservative estimates are consistently between 5-10% of production costs (equivalent to US$ 1.5 to 3 billion yr(-1)), illustrating the need for effective mitigation methods and technologies. The control of biofouling in aquaculture is achieved through the avoidance of natural recruitment, physical removal and the use of antifoulants. However, the continued rise and expansion of the aquaculture industry and the increasingly stringent legislation for biocides in food production necessitates the development of innovative antifouling strategies. These must meet environmental, societal, and economic benchmarks while effectively preventing the settlement and growth of resilient multi-species consortia of biofouling organisms.

  4. Marine biofouling of surfaces: morphology, and nanomechanics of Barnacle Cyprid adhesion proteins by AFM

    NARCIS (Netherlands)

    Phang, In Yee

    2008-01-01

    The understanding of biointerfaces in contact with seawater is crucially important in tackling the problems of marine biofouling. Such biointerfaces involve the bioadhesives used by marine organisms to attach temporary or permanently to the surfaces immersed in water. The aim of this Thesis is to ad

  5. The construction of a zwitterionic PVDF membrane surface to improve biofouling resistance.

    Science.gov (United States)

    Shen, Xiang; Zhao, Yiping; Chen, Li

    2013-09-01

    Biofouling of membrane surfaces by the attachment of microorganisms is one of the major obstacles for ensuring the effectiveness of membrane separation processes. This work presents the construction of a zwitterionic PVDF membrane surface with improved resistance to biofouling. An amphiphilic copolymer of poly(vinylidene fluoride)-graft-poly(N,N-dimethylamino-2-ethylmethacrylate) (PVDF-g-PDMAEMA) was first synthesized via radical graft copolymerization and then the flat membrane was cast with immersed phase inversion. The PDMAEMA side chains tended to aggregate on the membrane surface, pore surface and internal pore channel surface, and were converted with 1,3-propane sultone (1,3-PS) to yield a zwitterionic membrane surface. A higher conversion of PDMAEMA chains and distribution of zwitterions were obtained using a longer treatment time. A biofouling assay indicated that incorporation of zwitterions suppressed the adsorption of extracellular polymer substances and the adhesion of Escherichia coli bacterial cells to the membrane surface, endowing the membrane with a high flux recovery and biofouling resistance in the filtration process.

  6. Novel mussel-inspired injectable self-healing hydrogel with anti-biofouling property.

    Science.gov (United States)

    Li, Lin; Yan, Bin; Yang, Jingqi; Chen, Lingyun; Zeng, Hongbo

    2015-02-18

    A novel mussel-inspired injectable hydrogel with self-healing and anti-biofouling capabilities is developed and it possesses great potential as a drug-delivery carrier. The hydrogel can heal autonomously from repeated structural damage and also effectively prevent non-specific cell attachment and biofilm formation.

  7. Mitigation of marine biofouling on tubes of open rack vaporizers using electromagnetic fields.

    Science.gov (United States)

    Trueba, Alfredo; Vega, Luis M; García, Sergio; Otero, Félix M; Madariaga, Ernesto

    2016-01-01

    This study quantitatively evaluates the antifouling action of the continuous physical treatment with electromagnetic fields (EMFs) of seawater used as heat exchanger fluid in an open rack vaporizer (ORV) pilot plant to reduce the growth of biofouling on external rib-tube surfaces. The results demonstrate that the biofilm adhered on the treated rib-tubes was reduced by 33% in thickness and by 44% in dissolved solids regarding the biofilm adhered on the untreated control rib-tubes. The lower conductivity and Ca(2+) and Mg(2+) ionic content in the effluent of the treated seawater confirmed that the EMFs accelerated the process of ionic calcium nucleation and precipitation as calcium carbonate. The precipitation of ions dissolved affected the inter-molecular interactions among extracellular polymers, thereby weakening the biofouling film matrix and reducing its adhesion capacity. The drag of small particles by the flow of seawater had an erosive action and decreased the biofouling film thickness. Consequently, the antifouling methods treatment with EMFs allowed reduce the negative effect that the biofouling have for the heat transfer equipment used in the regasification process and keep the highest techno-economic operating conditions.

  8. The Effect of Hull Biofouling on Parameters Characterising Ship Propulsion System Efficiency

    Directory of Open Access Journals (Sweden)

    Tarełko Wiesła

    2015-01-01

    Full Text Available One of most important issues concerning technical objects is the increase of their operating performance. For a ship this performance mainly depends on the efficiency of its main pro-pulsion system and the resistance generated during its motion on water. The overall ship re-sistance, in turn, mainly depends on the hull friction resistance, closely related with the pres-ence of different types of roughness on the hull surface, including underwater part biofouling. The article analyses the effect of hull biofouling on selected parameters characterising the efficiency of the ship propulsion system with adjustable propeller. For this purpose a two-year research experiment was performed on a sailing vessel during its motor navigation phases. Based on the obtained results, three groups of characteristics were worked out for different combinations of engine rotational speed and adjustable propeller pitch settings. The obtained results have revealed that the phenomenon of underwater hull biofouling affects remarkably the parameters characterising propulsion system efficiency. In particular, the development of the biofouling layer leads to significant reduction of the speed of navigation.

  9. Systematic analysis of micromixers to minimize biofouling on reverse osmosis membranes.

    Science.gov (United States)

    Altman, Susan J; McGrath, Lucas K; Jones, Howland D T; Sanchez, Andres; Noek, Rachel; Clem, Paul; Cook, Adam; Ho, Clifford K

    2010-06-01

    Micromixers, UV-curable epoxy traces printed on the surface of a reverse osmosis membrane, were tested on a cross-flow system to determine their success at reducing biofouling. Biofouling was quantified by measuring the rate of permeate flux decline and the median bacteria concentration on the surface of the membrane (as determined by fluorescence intensity counts due to nucleic acid stains as measured by hyperspectral imaging). The micromixers do not appear to significantly increase the pressure needed to maintain the same initial permeate flux and salt rejection. Chevrons helped prevent biofouling of the membranes in comparison with blank membranes. The chevron design controlled where the bacteria adhered to the membrane surface. However, blank membranes with spacers had a lower rate of permeate flux decline than the membranes with chevrons despite having greater bacteria concentrations on their surfaces. With better optimization of the micromixer design, the micromixers could be used to control where the bacteria will adhere to the surface and create a more biofouling resistant membrane that will help to drive down the cost of water treatment.

  10. Do biological-based strategies hold promise to biofouling control in MBRs?

    KAUST Repository

    Malaeb, Lilian

    2013-10-01

    Biofouling in membrane bioreactors (MBRs) remains a primary challenge for their wider application, despite the growing acceptance of MBRs worldwide. Research studies on membrane fouling are extensive in the literature, with more than 200 publications on MBR fouling in the last 3 years; yet, improvements in practice on biofouling control and management have been remarkably slow. Commonly applied cleaning methods are only partially effective and membrane replacement often becomes frequent. The reason for the slow advancement in successful control of biofouling is largely attributed to the complex interactions of involved biological compounds and the lack of representative-for-practice experimental approaches to evaluate potential effective control strategies. Biofouling is driven by microorganisms and their associated extra-cellular polymeric substances (EPS) and microbial products. Microorganisms and their products convene together to form matrices that are commonly treated as a black box in conventional control approaches. Biological-based antifouling strategies seem to be a promising constituent of an effective integrated control approach since they target the essence of biofouling problems. However, biological-based strategies are in their developmental phase and several questions should be addressed to set a roadmap for translating existing and new information into sustainable and effective control techniques. This paper investigates membrane biofouling in MBRs from the microbiological perspective to evaluate the potential of biological-based strategies in offering viable control alternatives. Limitations of available control methods highlight the importance of an integrated anti-fouling approach including biological strategies. Successful development of these strategies requires detailed characterization of microorganisms and EPS through the proper selection of analytical tools and assembly of results. Existing microbiological/EPS studies reveal a number of

  11. Do biological-based strategies hold promise to biofouling control in MBRs?

    Science.gov (United States)

    Malaeb, Lilian; Le-Clech, Pierre; Vrouwenvelder, Johannes S; Ayoub, George M; Saikaly, Pascal E

    2013-10-01

    Biofouling in membrane bioreactors (MBRs) remains a primary challenge for their wider application, despite the growing acceptance of MBRs worldwide. Research studies on membrane fouling are extensive in the literature, with more than 200 publications on MBR fouling in the last 3 years; yet, improvements in practice on biofouling control and management have been remarkably slow. Commonly applied cleaning methods are only partially effective and membrane replacement often becomes frequent. The reason for the slow advancement in successful control of biofouling is largely attributed to the complex interactions of involved biological compounds and the lack of representative-for-practice experimental approaches to evaluate potential effective control strategies. Biofouling is driven by microorganisms and their associated extra-cellular polymeric substances (EPS) and microbial products. Microorganisms and their products convene together to form matrices that are commonly treated as a black box in conventional control approaches. Biological-based antifouling strategies seem to be a promising constituent of an effective integrated control approach since they target the essence of biofouling problems. However, biological-based strategies are in their developmental phase and several questions should be addressed to set a roadmap for translating existing and new information into sustainable and effective control techniques. This paper investigates membrane biofouling in MBRs from the microbiological perspective to evaluate the potential of biological-based strategies in offering viable control alternatives. Limitations of available control methods highlight the importance of an integrated anti-fouling approach including biological strategies. Successful development of these strategies requires detailed characterization of microorganisms and EPS through the proper selection of analytical tools and assembly of results. Existing microbiological/EPS studies reveal a number of

  12. Inhibition of phagocytosis of complement C3- or immunoglobulin G-coated particles and of C3bi binding by monoclonal antibodies to a monocyte-granulocyte membrane glycoprotein (Mol).

    OpenAIRE

    Arnaout, M. A.; Todd, R F; Dana, N; Melamed, J; Schlossman, S F; Colten, H R

    1983-01-01

    Events that lead to phagocytosis of complement (C3)- or IgG-coated particles after their interaction with specific cell surface receptors are poorly understood. Two mouse monoclonal antibodies (an IgM and an IgG2a) to a human granulocyte-monocyte surface membrane differentiation antigen (Mol) inhibited ingestion by granulocytes both of oil Red O particles opsonized with normal human serum or with IgG and of sheep erythrocytes sensitized with IgG. In addition, they specifically inhibited roset...

  13. Anticorrosive coatings: a review

    DEFF Research Database (Denmark)

    Sørensen, Per Aggerholm; Kiil, Søren; Dam-Johansen, Kim;

    2009-01-01

    of volatile organic compounds (VOCs) have caused significant changes in the anticorrosive coating industry. The requirement for new VOC-compliant coating technologies means that coating manufacturers can no longer rely on the extensive track record of their time-served products to convince consumers......, and inhibitive coatings are outlined. In the past decades, several alternatives to organic solvent-borne coatings have reached the commercial market. This review also presents some of these technologies and discusses some of their advantages and limitations. Finally, some of the mechanisms leading to degradation...... of their suitability for use. An important aspect in the development of new VOC-compliant, high-performance anticorrosive coating systems is a thorough knowledge of the components in anticorrosive coatings, their interactions, their advantages and limitations, as well as a detailed knowledge on the failure modes...

  14. Effects of Water Quality on Activity of Biofouling in Recirculating Cooling Water System%循环冷却水水质对生物粘泥活性的影响研究

    Institute of Scientific and Technical Information of China (English)

    马涛; 赵朝成; 刘芳; 张培; 夏璐

    2011-01-01

    受补充水水质的影响,循环冷却水水质会在一定范围内波动,为此考察了营养物质(BOD5、TP、NH4+-N)、颗粒物质(CaCO3)、无机离子(Ca2+、Mg2+、Na+、Fe3+)对循环水中生物粘泥活性的影响.研究结果表明,循环冷却水水质对生物粘泥的活性有较大影响,当BOD5≤25 mg/L、NH4+-N<5 mg/L、TP≤1 mg/L时,可将粘泥活性控制在较低水平.在低营养水平条件下,分别维持CaCO3<40 mg/L、Ca2+<100 mg/L、Mg2+≤100 mg/L、Na+<50 mg/L、Fe3+<0.5 mg/L时,可有效抑制粘泥活性,控制粘泥中细菌的生长繁殖.%Due to the influence of make-up water quality, the water quality of recirculating cooling water system would fluctuate within a certain range. So the effects of necessary nutrients ( BOD5 , TP and NH4+ - N), suspended particles (CaCO3) and inorganic ion (Ca2 + , Mg2+ , Na + and Fe3 + ) content on activity of biofouling in recirculating cooling water system were investigated. The results show that the water quality of recirculating cooling water system has significant effect on the activity of biofouling. When BOD5 and TP are equal to or less than 25 mg/L and 1 mg/L respectively, NH4+ - N is less than 5 mg/L,the activity of biofouling can be controlled at a low level. Under low nutrient conditions, keeping CaCO3,Ca2+ , Na + , Fe3+ and Mg2+ at less than 40 mg/L, 100 mg/L, 50 mg/L, 0.5 mg/L and equal to or less than 100 mg/L respectively can effectively inhibit the activity of biofouling and control the growth and reproduction of bacteria in biofouling.

  15. Biofouling community composition across a range of environmental conditions and geographical locations suitable for floating marine renewable energy generation.

    Science.gov (United States)

    Macleod, Adrian K; Stanley, Michele S; Day, John G; Cook, Elizabeth J

    2016-01-01

    Knowledge of biofouling typical of marine structures is essential for engineers to define appropriate loading criteria in addition to informing other stakeholders about the ecological implications of creating novel artificial environments. There is a lack of information regarding biofouling community composition (including weight and density characteristics) on floating structures associated with future marine renewable energy generation technologies. A network of navigation buoys were identified across a range of geographical areas, environmental conditions (tidal flow speed, temperature and salinity), and deployment durations suitable for future developments. Despite the perceived importance of environmental and temporal factors, geographical location explained the greatest proportion of the observed variation in community composition, emphasising the importance of considering geography when assessing the impact of biofouling on device functioning and associated ecology. The principal taxa associated with variation in biofouling community composition were mussels (Mytilus edulis), which were also important when determining loading criteria.

  16. Evaluation of the sea anemone Anthothoe albocincta as an augmentative biocontrol agent for biofouling on artificial structures.

    Science.gov (United States)

    Atalah, Javier; Bennett, Holly; Hopkins, Grant A; Forrest, Barrie M

    2013-01-01

    Augmentative biocontrol, defined as the use of indigenous natural enemies to control pest populations, has not been explored extensively in marine systems. This study tested the potential of the anemone Anthothoe albocincta as a biocontrol agent for biofouling on submerged artificial structures. Biofouling biomass was negatively related to anemone cover. Treatments with high anemone cover (>35%) led to significant changes in biofouling assemblages compared to controls. Taxa that contributed to these changes differed among sites, but included reductions in cover of problematic fouling organisms, such as solitary ascidians and bryozoans. In laboratory trials, A. albocincta substantially prevented the settlement of larvae of the bryozoan Bugula neritina when exposed to three levels of larval dose, suggesting predation as an important biocontrol mechanism, in addition to space pre-emption. This study demonstrated that augmentative biocontrol using anemones has the potential to reduce biofouling on marine artificial structures, although considerable further work is required to refine this tool before its application.

  17. Self-Healing Underwater Superoleophobic and Antibiofouling Coatings Based on the Assembly of Hierarchical Microgel Spheres.

    Science.gov (United States)

    Chen, Kunlin; Zhou, Shuxue; Wu, Limin

    2016-01-26

    Marine biofouling has been plaguing people for thousands of years. While various strategies have been developed for antifouling (including superoleophobic) coatings, none of these exhibits self-healing properties because the bestowal of a zoetic self-repairing function to lifeless artificial water/solid interfacial materials is usually confronted with tremendous challenges. Here, we present a self-repairing underwater superoleophobic and antibiofouling coating through the self-assembly of hydrophilic polymeric chain modified hierarchical microgel spheres. The obtained surface material not only has excellent underwater superoleophobicity but also has very good subaqueous antibiofouling properties. More importantly, this surface material can recover the oil- and biofouling-resistant properties once its surface is mechanically damaged, similar to the skins of some marine organisms such as sharks or whales. This approach is feasible and easily mass-produced and could open a pathway and possibility for the fabrication of other self-healing functional water/solid interfacial materials. PMID:26687925

  18. Biofouling evaluation in the seawater cooling circuit of an operating coastal power plant

    International Nuclear Information System (INIS)

    Chlorination is the most commonly used method of biofouling control in cooling water systems of coastal power stations. In the present study, we report results of extensive sampling in different sections of the cooling water system of an operating power station undertaken during three consecutive maintenance shutdowns. The power plant employed continuous low level chlorination (0.2 ± 0.1 mg L-1 TRO) with twice-a-week booster dosing (0.4 ± 0.1 mg L-1 TRO for 8 hours). In addition, the process seawater heat exchangers received supplementary dosing of bromide treatment (0.2 ± 0.1 mg L-1 TRO for 1 hour in every 8 h shift). Biofouling samples were collected from the cooling water conduits, heat exchanger water boxes, pipelines, heated discharge conduits and outfall section during the annual maintenance shutdown of the plant in the years 2007, 2008 and 2009. Simultaneous monitoring of biofouling on test coupons in coastal waters enabled direct comparison of fouling situation on test panels and that in the cooling system. The data showed significant reduction in biofouling inside the cooling circuit as compared to the coastal waters. However, significant amount of fouling was still evident at several places, indicating inadequacy of the biocide treatment regime. The maximum load of 31.3 kg m2 y-1 was observed in the conduits leading to the process seawater heat exchangers (PSW-HX) and the minimum of 1.3 kg m2 y-1 was observed in the outfall section. Fouling loads of 12.2 - 14.7 kg m2 y-1 were observed in the concrete conduits feeding the main condensers. Bromide treatment ahead of the PSW-HX could marginally reduce the fouling load in the downstream section of the dosing point; the HX inlets still showed good biofouling. Species diversity across the cooling water system showed the pre-condenser section to be dominated by green mussels (Perna viridis), pearl oysters (Pinctada sp.) and edible oysters (Crassostrea sp.), whereas the post-condenser section and heat

  19. Characterization and effect of biofouling on polyamide reverse osmosis and nanofiltration membrane surfaces.

    Science.gov (United States)

    Khan, Mohiuddin Md Taimur; Stewart, Philip S; Moll, David J; Mickols, William E; Nelson, Sara E; Camper, Anne K

    2011-02-01

    Biofouling is a major reason for flux decline in the performance of membrane-based water and wastewater treatment plants. Initial biochemical characterization of biofilm formation potential and biofouling on two commercially available membrane surfaces from FilmTec Corporation were investigated without filtration in laboratory rotating disc reactor systems. These surfaces were polyamide aromatic thin-film reverse osmosis (RO) (BW30) and semi-aromatic nanofiltration (NF270) membranes. Membrane swatches were fixed on removable coupons and exposed to water with indigenous microorganisms supplemented with 1.5 mg l(-1) organic carbon under continuous flow. After biofilms formed, the membrane swatches were removed for analyses. Staining and epifluorescence microscopy revealed more cells on the RO than on the NF surface. Based on image analyses of 5-μm thick cryo-sections, the accumulation of hydrated biofoulants on the RO and NF surfaces exceeded 0.74 and 0.64 μm day(-1), respectively. As determined by contact angle the biofoulants increased the hydrophobicity up to 30° for RO and 4° for NF surfaces. The initial difference between virgin RO and NO hydrophobicities was ∼5°, which increased up to 25° after biofoulant formation. The initial roughness of RO and NF virgin surfaces (75.3 nm and 8.2 nm, respectively) increased to 48 nm and 39 nm after fouling. A wide range of changes of the chemical element mass percentages on membrane surfaces was observed with X-ray photoelectron spectroscopy. The initial chemical signature on the NF surface was better restored after cleaning than the RO membrane. All the data suggest that the semi-aromatic NF surface was more biofilm resistant than the aromatic RO surface. The morphology of the biofilm and the location of active and dead cell zones could be related to the membrane surface properties and general biofouling accumulation was associated with changes in the surface chemistry of the membranes, suggesting the validity of

  20. Semisubmersible oil platforms: understudied and potentially major vectors of biofouling-mediated invasions.

    Science.gov (United States)

    Yeo, Darren C J; Ahyong, Shane T; Lodge, David M; Ng, Peter K L; Naruse, Tohru; Lane, David J W

    2010-01-01

    Biofouling has long been recognised as a major pathway for the introduction of non-indigenous species. This study records the decapods and stomatopod crustaceans fouling a semisubmersible oil platform dry docked for hull cleaning in Jurong Port, Singapore. Of the 25 species of decapods identified, 13 were non-indigenous and represent new records to Singapore waters. Of these, the crabs Glabropilumnus seminudus and Carupa tenuipes are known to be invasive in other parts of the world. The stomatopod, Gonodactylaceus randalli, is the first mantis shrimp recorded in a biofouling community. The richness and diversity of this fouling community, consisting of many vagile species, highlights the difference between platforms and ships. With the expansion of maritime oil and gas exploration, the threat posed by an expanded fleet of semisubmersible oil platforms translocating non-indigenous fouling communities across biogeographical boundaries is very serious. Scientists, policy-makers, and stakeholders should turn their attention to this growing problem. PMID:19927240

  1. Light as a key driver of freshwater biofouling surface roughness in an experimental hydrocanal pipe rig.

    Science.gov (United States)

    Ravizza, Matilde; Giosio, Dean; Henderson, Alan; Hovenden, Mark; Hudson, Monica; Salleh, Sazlina; Sargison, Jane; Shaw, Jennifer L; Walker, Jessica; Hallegraeff, Gustaaf

    2016-07-01

    Biofouling in canals and pipelines used for hydroelectric power generation decreases the flow capacity of conduits. A pipeline rig was designed consisting of test sections of varying substrata (PVC, painted steel) and light levels (transparent, frosted, opaque). Stalk-forming diatoms were abundant in both the frosted and transparent PVC pipes but negligible in the painted steel and opaque PVC pipes. Fungi were slightly more abundant in the painted steel pipe but equally present in all the other pipes while bacterial diversity was similar in all pipes. Photosynthetically functional biofouling (mainly diatoms) was able to develop in near darkness. Different biological fouling compositions generated differing friction factors. The highest friction factor was observed in the transparent pipe (densest diatom fouling), the lowest peak friction for the opaque PVC pipe (lowest fouling biomass), and with the painted steel pipe (high fouling biomass, but composed of fungal and bacterial crusts) being intermediate between the opaque and frosted PVC pipes. PMID:27244248

  2. 3D imaging provides a high-resolution, volumetric approach for analyzing biofouling.

    Science.gov (United States)

    First, Matthew R; Policastro, Steven A; Strom, Matthew J; Riley, Scott C; Robbins-Wamsley, Stephanie H; Drake, Lisa A

    2014-01-01

    A volumetric approach for determining the fouling burden on surfaces is presented, consisting of a 3D camera imaging system with fine (5 μm) resolution. Panels immersed in an estuary on the southwest coast of Florida, USA were imaged and the data were used to quantify seasonal changes in the biofouling community. Test panels, which were submerged in seawater for up to one year, were analyzed before and after gentle scrubbing to quantify the biovolume of the total fouling community (ie soft and hard organisms) and the hard fouling community. Total biofouling ranged from 0.01 to 1.16 cm(3) cm(-2) throughout the immersion period; soft fouling constituted 22-87% of the total biovolume. In the future, this approach may be used to inform numerical models of fluid-surface interfaces and to evaluate, with high resolution, the morphology of fouling organisms in response to antifouling technologies.

  3. Light as a key driver of freshwater biofouling surface roughness in an experimental hydrocanal pipe rig.

    Science.gov (United States)

    Ravizza, Matilde; Giosio, Dean; Henderson, Alan; Hovenden, Mark; Hudson, Monica; Salleh, Sazlina; Sargison, Jane; Shaw, Jennifer L; Walker, Jessica; Hallegraeff, Gustaaf

    2016-07-01

    Biofouling in canals and pipelines used for hydroelectric power generation decreases the flow capacity of conduits. A pipeline rig was designed consisting of test sections of varying substrata (PVC, painted steel) and light levels (transparent, frosted, opaque). Stalk-forming diatoms were abundant in both the frosted and transparent PVC pipes but negligible in the painted steel and opaque PVC pipes. Fungi were slightly more abundant in the painted steel pipe but equally present in all the other pipes while bacterial diversity was similar in all pipes. Photosynthetically functional biofouling (mainly diatoms) was able to develop in near darkness. Different biological fouling compositions generated differing friction factors. The highest friction factor was observed in the transparent pipe (densest diatom fouling), the lowest peak friction for the opaque PVC pipe (lowest fouling biomass), and with the painted steel pipe (high fouling biomass, but composed of fungal and bacterial crusts) being intermediate between the opaque and frosted PVC pipes.

  4. Vessel generator noise as a settlement cue for marine biofouling species.

    Science.gov (United States)

    McDonald, J I; Wilkens, S L; Stanley, J A; Jeffs, A G

    2014-01-01

    Underwater noise is increasing globally, largely due to increased vessel numbers and international ocean trade. Vessels are also a major vector for translocation of non-indigenous marine species which can have serious implications for biosecurity. The possibility that underwater noise from fishing vessels may promote settlement of biofouling on hulls was investigated for the ascidian Ciona intestinalis. Spatial differences in biofouling appear to be correlated with spatial differences in the intensity and frequency of the noise emitted by the vessel's generator. This correlation was confirmed in laboratory experiments where C. intestinalis larvae showed significantly faster settlement and metamorphosis when exposed to the underwater noise produced by the vessel generator. Larval survival rates were also significantly higher in treatments exposed to vessel generator noise. Enhanced settlement attributable to vessel generator noise may indicate that vessels not only provide a suitable fouling substratum, but vessels running generators may be attracting larvae and enhancing their survival and growth.

  5. Construction of phospholipid anti-biofouling multilayer on biomedical PET surfaces

    International Nuclear Information System (INIS)

    The biomimetic phospholipid anti-biofouling multilayers were constructed on the biomedical poly(ethylene terephthalate) (PET) through the combination of layer-by-layer assembly and Michael addition reaction. Two biomacromolecules with opposite charges, alginate and chitosan, were sequentially adsorbed onto PET samples. The assembled multilayer was subsequently crosslinked with glutaraldehyde and biomimetic phospholipids was introduced into the assembled multilayer through the Michael addition of 2-methacryloyloxyethyl phosphorylcholine (MPC). The multilayer and phospholipid-modified PETs showed excellent hemocompatibility

  6. Preparation and evaluation of biocide-loaded particles to control the biofouling zebra mussel, Dreissena polymorpha

    OpenAIRE

    R. Costa; Aldridge, D. C.; Moggridge, G. D.

    2011-01-01

    The freshwater zebra mussel Dreissena polymorpha is a powerful biofouling bivalve, which has tremendous impact on industrial facilities whose operation depends on the intensive use of freshwater, such as waterworks and power stations. The control of the pest in industrial environments remains a major challenge due to low selectivity over non-target organisms and the expense of the large quantities of biocides required. A novel delivery technique involving the encapsulation of a toxin within h...

  7. Marine biofouling of surfaces: morphology, and nanomechanics of Barnacle Cyprid adhesion proteins by AFM

    OpenAIRE

    Phang, In Yee

    2008-01-01

    The understanding of biointerfaces in contact with seawater is crucially important in tackling the problems of marine biofouling. Such biointerfaces involve the bioadhesives used by marine organisms to attach temporary or permanently to the surfaces immersed in water. The aim of this Thesis is to address a particular problem, i.e. barnacle adhesion, to the biointerface and the corresponding fouling process. We try to understand the first steps of the fouling process of this species, and help ...

  8. Nitric oxide treatment for the control of reverse osmosis membrane biofouling.

    Science.gov (United States)

    Barnes, Robert J; Low, Jiun Hui; Bandi, Ratnaharika R; Tay, Martin; Chua, Felicia; Aung, Theingi; Fane, Anthony G; Kjelleberg, Staffan; Rice, Scott A

    2015-04-01

    Biofouling remains a key challenge for membrane-based water treatment systems. This study investigated the dispersal potential of the nitric oxide (NO) donor compound, PROLI NONOate, on single- and mixed-species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis (RO) membranes. The potential of PROLI NONOate to control RO membrane biofouling was also examined. Confocal microscopy revealed that PROLI NONOate exposure induced biofilm dispersal in all but two of the bacteria tested and successfully dispersed mixed-species biofilms. The addition of 40 μM PROLI NONOate at 24-h intervals to a laboratory-scale RO system led to a 92% reduction in the rate of biofouling (pressure rise over a given period) by a bacterial community cultured from an industrial RO membrane. Confocal microscopy and extracellular polymeric substances (EPS) extraction revealed that PROLI NONOate treatment led to a 48% reduction in polysaccharides, a 66% reduction in proteins, and a 29% reduction in microbial cells compared to the untreated control. A reduction in biofilm surface coverage (59% compared to 98%, treated compared to control) and average thickness (20 μm compared to 26 μm, treated compared to control) was also observed. The addition of PROLI NONOate led to a 22% increase in the time required for the RO module to reach its maximum transmembrane pressure (TMP), further indicating that NO treatment delayed fouling. Pyrosequencing analysis revealed that the NO treatment did not significantly alter the microbial community composition of the membrane biofilm. These results present strong evidence for the application of PROLI NONOate for prevention of RO biofouling.

  9. Composition and Variability of Biofouling Organisms in Seawater Reverse Osmosis Desalination Plants ▿ †

    OpenAIRE

    Zhang, Minglu; Jiang, Sunny; Tanuwidjaja, Dian; Voutchkov, Nikolay; Hoek, Eric M. V.; Cai, Baoli

    2011-01-01

    Seawater reverse osmosis (SWRO) membrane biofouling remains a common challenge in the desalination industry, but the marine bacterial community that causes membrane fouling is poorly understood. Microbial communities at different stages of treatment processes (intake, cartridge filtration, and SWRO) of a desalination pilot plant were examined by both culture-based and culture-independent approaches. Bacterial isolates were identified to match the genera Shewanella, Alteromonas, Vibrio, and Ce...

  10. Nitric oxide treatment for the control of reverse osmosis membrane biofouling.

    Science.gov (United States)

    Barnes, Robert J; Low, Jiun Hui; Bandi, Ratnaharika R; Tay, Martin; Chua, Felicia; Aung, Theingi; Fane, Anthony G; Kjelleberg, Staffan; Rice, Scott A

    2015-04-01

    Biofouling remains a key challenge for membrane-based water treatment systems. This study investigated the dispersal potential of the nitric oxide (NO) donor compound, PROLI NONOate, on single- and mixed-species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis (RO) membranes. The potential of PROLI NONOate to control RO membrane biofouling was also examined. Confocal microscopy revealed that PROLI NONOate exposure induced biofilm dispersal in all but two of the bacteria tested and successfully dispersed mixed-species biofilms. The addition of 40 μM PROLI NONOate at 24-h intervals to a laboratory-scale RO system led to a 92% reduction in the rate of biofouling (pressure rise over a given period) by a bacterial community cultured from an industrial RO membrane. Confocal microscopy and extracellular polymeric substances (EPS) extraction revealed that PROLI NONOate treatment led to a 48% reduction in polysaccharides, a 66% reduction in proteins, and a 29% reduction in microbial cells compared to the untreated control. A reduction in biofilm surface coverage (59% compared to 98%, treated compared to control) and average thickness (20 μm compared to 26 μm, treated compared to control) was also observed. The addition of PROLI NONOate led to a 22% increase in the time required for the RO module to reach its maximum transmembrane pressure (TMP), further indicating that NO treatment delayed fouling. Pyrosequencing analysis revealed that the NO treatment did not significantly alter the microbial community composition of the membrane biofilm. These results present strong evidence for the application of PROLI NONOate for prevention of RO biofouling. PMID:25636842

  11. Anti-biofouling property of vanillin on Aeromonas hydrophila initial biofilm on various membrane surfaces.

    Science.gov (United States)

    Ponnusamy, K; Kappachery, S; Thekeettle, M; Song, J H; Kweon, J H

    2013-09-01

    Biofouling is a serious problem on filter membranes of water purification systems due to formation of bacterial biofilms, which can be detrimental to the membrane performance. Biofouling occurs on membrane surface and therefore greatly influences the physical and chemical aspects of the surface. Several membranes including microfiltration, ultrafiltration, and reverse osmosis (RO) membranes were used to learn about the anti-biofouling properties of vanillin affecting the membrane performances. Vanillin has been recognized as a potential quorum quenching compound for Aeromonas hydrophila biofilms. The initial attachment and dynamics of biofilm growth were monitored using scanning electron microscopy and confocal laser scanning microscopy. Biofilm quantities were measured using a plate count method and total protein determinations. Vanillin addition was effective in the prevention of biofilm formation on the tested membrane surfaces. Among the membranes, RO membranes made with cellulose acetate showed the most substantial reduction of biofilm formation by addition of vanillin. The biofilm reduction was confirmed by the results of surface coverage, biomass and protein accumulation. The HPLC spectrum of the spent culture with vanillin addition showed that vanillin may interfere with quorum sensing molecules and thus prevent the formation of the biofilms.

  12. Effect of water temperature on biofouling development in reverse osmosis membrane systems

    KAUST Repository

    Farhat, N.M.

    2016-07-14

    Understanding the factors that determine the spatial and temporal biofilm development is a key to formulate effective control strategies in reverse osmosis membrane systems for desalination and wastewater reuse. In this study, biofilm development was investigated at different water temperatures (10, 20, and 30 °C) inside a membrane fouling simulator (MFS) flow cell. The MFS studies were done at the same crossflow velocity with the same type of membrane and spacer materials, and the same feed water type and nutrient concentration, differing only in water temperature. Spatially resolved biofilm parameters such as oxygen decrease rate, biovolume, biofilm spatial distribution, thickness and composition were measured using in-situ imaging techniques. Pressure drop (PD) increase in time was used as a benchmark as to when to stop the experiments. Biofilm measurements were performed daily, and experiments were stopped once the average PD increased to 40 mbar/cm. The results of the biofouling study showed that with increasing feed water temperature (i) the biofilm activity developed faster, (ii) the pressure drop increased faster, while (iii) the biofilm thickness decreased. At an average pressure drop increase of 40 mbar/cm over the MFS for the different feed water temperatures, different biofilm activities, structures, and quantities were found, indicating that diagnosis of biofouling of membranes operated at different or varying (seasonal) feed water temperatures may be challenging. Membrane installations with a high temperature feed water are more susceptible to biofouling than installations fed with low temperature feed water.

  13. Effect of water temperature on biofouling development in reverse osmosis membrane systems.

    Science.gov (United States)

    Farhat, N M; Vrouwenvelder, J S; Van Loosdrecht, M C M; Bucs, Sz S; Staal, M

    2016-10-15

    Understanding the factors that determine the spatial and temporal biofilm development is a key to formulate effective control strategies in reverse osmosis membrane systems for desalination and wastewater reuse. In this study, biofilm development was investigated at different water temperatures (10, 20, and 30 °C) inside a membrane fouling simulator (MFS) flow cell. The MFS studies were done at the same crossflow velocity with the same type of membrane and spacer materials, and the same feed water type and nutrient concentration, differing only in water temperature. Spatially resolved biofilm parameters such as oxygen decrease rate, biovolume, biofilm spatial distribution, thickness and composition were measured using in-situ imaging techniques. Pressure drop (PD) increase in time was used as a benchmark as to when to stop the experiments. Biofilm measurements were performed daily, and experiments were stopped once the average PD increased to 40 mbar/cm. The results of the biofouling study showed that with increasing feed water temperature (i) the biofilm activity developed faster, (ii) the pressure drop increased faster, while (iii) the biofilm thickness decreased. At an average pressure drop increase of 40 mbar/cm over the MFS for the different feed water temperatures, different biofilm activities, structures, and quantities were found, indicating that diagnosis of biofouling of membranes operated at different or varying (seasonal) feed water temperatures may be challenging. Membrane installations with a high temperature feed water are more susceptible to biofouling than installations fed with low temperature feed water.

  14. Atomically Bonded Transparent Superhydrophobic Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Aytug, Tolga [ORNL

    2015-08-01

    Maintaining clarity and avoiding the accumulation of water and dirt on optically transparent surfaces such as US military vehicle windshields, viewports, periscope optical head windows, and electronic equipment cover glasses are critical to providing a high level of visibility, improved survivability, and much-needed safety for warfighters in the field. Through a combination of physical vapor deposition techniques and the exploitation of metastable phase separation in low-alkali borosilicate, a novel technology was developed for the fabrication of optically transparent, porous nanostructured silica thin film coatings that are strongly bonded to glass platforms. The nanotextured films, initially structurally superhydrophilic, exhibit superior superhydrophobicity, hence antisoiling ability, following a simple but robust modification in surface chemistry. The surfaces yield water droplet contact angles as high as 172°. Moreover, the nanostructured nature of these coatings provides increased light scattering in the UV regime and reduced reflectivity (i.e., enhanced transmission) over a broad range of the visible spectrum. In addition to these functionalities, the coatings exhibit superior mechanical resistance to abrasion and are thermally stable to temperatures approaching 500°C. The overall process technology relies on industry standard equipment and inherently scalable manufacturing processes and demands only nontoxic, naturally abundant, and inexpensive base materials. Such coatings, applied to the optical components of current and future combat equipment and military vehicles will provide a significant strategic advantage for warfighters. The inherent self-cleaning properties of such superhydrophobic coatings will also mitigate biofouling of optical windows exposed to high-humidity conditions and can help decrease repair/replacement costs, reduce maintenance, and increase readiness by limiting equipment downtime.

  15. Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: linking biofouling layer morphology with flux stabilization.

    Science.gov (United States)

    Akhondi, Ebrahim; Wu, Bing; Sun, Shuyang; Marxer, Brigit; Lim, Weikang; Gu, Jun; Liu, Linbo; Burkhardt, Michael; McDougald, Diane; Pronk, Wouter; Fane, Anthony G

    2015-03-01

    In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range of 3.6 L/m(2) h (21 ± 1 °C, 40 mbar) to 7.3 L/m(2) h (29 ± 1 °C, 100 mbar) after slight fluctuations and remained constant for the duration of the experiments (almost 3 months). An increase in biofouling layer thickness and a variable biofouling layer structure were observed over time by optical coherence tomography and confocal laser scanning microscopy. The presence of eukaryotic organisms in the biofouling layer was observed by light microscopy and the microbial community structure of the biofouling layer was analyzed by sequences of 16S rRNA genes. The magnitude of permeate flux was associated with the combined effect of the biofouling layer thickness and structure. Changes in the biofouling layer structure were attributed to (1) the movement and predation behaviour of the eukaryotic organisms which increased the heterogeneous nature of the biofouling layer; (2) the bacterial debris generated by eukaryotic predation activity which reduced porosity; (3) significant shifts of the dominant bacterial species over time that may have influenced the biofouling layer structure. As expected, most of the particles and colloids in the feed seawater were removed by the GDM process, which led to a lower RO fouling potential. However, the dissolved organic carbon in the

  16. Early non-destructive biofouling detection in spiral wound RO Membranes using a mobile earth's field NMR

    KAUST Repository

    Fridjonsson, E.O.

    2015-04-20

    We demonstrate the use of Earth\\'s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (signal relaxation parameters T1, T2 and the total NMR signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  17. Application of fluorescently labelled lectins for the study of polysaccharides in biofilms with a focus on biofouling of nanofiltration membranes

    Directory of Open Access Journals (Sweden)

    Patrick Di Martino

    2016-07-01

    Full Text Available The biofilm state is the dominant microbial lifestyle in nature. A biofilm can be defined as cells organised as microcolonies embedded in an organic polymer matrix of microbial origin living at an interface between two different liquids, air and liquid, or solid and liquid. The biofilm matrix is made of extracellular polymeric substances, polysaccharides being considered as the major structural components of the matrix. Fluorescently labelled lectins have been widely used to stain microbial extracellular glycoconjugates in natural and artificial environments, and to study specific bacterial species or highly complex environments. Biofilm development at the membrane surface conducting to biofouling is one of the major problems encountered during drinking water production by filtration. Biofouling affects the durability and effectiveness of filtration membranes. Biofouling can be reduced by pretreatments in order to control two key parameters of water, the bioavailable organic matter concentration and the concentration of live bacteria. Nanofiltration (NF is a high technology process particularly suited to the treatment of surface waters to produce drinking water that is highly sensitive to biofouling. The development of strategies for fouling prevention and control requires characterizing the fouling material composition and organisation before and after NF membrane cleaning. The aim of this review is to present basics of biofilm analyses after staining with fluorescently labelled lectins and to focus on the use of fluorescent lectins and confocal laser scanning microscopy to analyse NF membrane biofouling.

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

    Science.gov (United States)

    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.

  19. Adhesion of monocytes to medical steel as used for vascular stents is mediated by the integrin receptor Mac-1 (CD11b/CD18; alphaM beta2) and can be inhibited by semiconductor coating.

    Science.gov (United States)

    Schuler, Pia; Assefa, Dawit; Ylänne, Jari; Basler, Nicole; Olschewski, Manfred; Ahrens, Ingo; Nordt, Thomas; Bode, Christoph; Peter, Karlheinz

    2003-01-01

    Implantation of stents into stenosed arteries helps to restore normal blood flow in ischemic organs. However, limited biocompatibility of the applied medical steel can cause acute thrombosis and long-term restenosis. Adhesion of monocytes to stent metal may participate in those acute and long-term complications of stent placement. Based on described prominent electrochemical properties of the interaction between the monocyte integrin receptor Mac-1 and its various ligands, we hypothesized, that this receptor is a central mediator of monocyte adhesion to stent metal and that semiconductor coating of medical steel reduces monocyte adhesion. Adhesion of monocytes on L-316 stainless steel was directly evaluated by light microscopy. Mac-1 could be identified as mediator of monocyte adhesion, since cell adhesion could be blocked by anti-Mac-1-antibodies, including the cross-reacting anti-GPIIb/IIIa antibody fragment abciximab. To further prove the central role of Mac-1, two CHO cell lines were generated expressing recombinant Mac-1 either as wild type, resulting in a low affinity receptor, or mutant with a GFFKR deletion of the alpha(M) subunit, resulting in a high affinity receptor. Indeed, adhesion was specific for Mac-1 and dependent on the affinity state of this integrin. Finally, we could demonstrate that Mac-1-mediated adhesion of monocytes to stents can be significantly inhibited by silicon carbide coating of the stent metal. In conclusion, the integrin Mac-1 and its affinity state could be identified as major mediators of monocyte adhesion on medical steel. As therapeutic strategies, the blockade of Mac-1 by antibodies or silicon carbide coating of steel inhibits monocyte adhesion on stents. PMID:12881037

  20. Enzymatic cleaning of biofouled thin-film composite reverse osmosis (RO) membrane operated in a biofilm membrane reactor.

    Science.gov (United States)

    Khan, Mohiuddin; Danielsen, Steffen; Johansen, Katja; Lorenz, Lindsey; Nelson, Sara; Camper, Anne

    2014-02-01

    Application of environmentally friendly enzymes to remove thin-film composite (TFC) reverse osmosis (RO) membrane biofoulants without changing the physico-chemical properties of the RO surface is a challenging and new concept. Eight enzymes from Novozyme A/S were tested using a commercially available biofouling-resistant TFC polyamide RO membrane (BW30, FilmTech Corporation, Dow Chemical Co.) without filtration in a rotating disk reactor system operated for 58 days. At the end of the operation, the accumulated biofoulants on the TFC RO surfaces were treated with the three best enzymes, Subtilisin protease and lipase; dextranase; and polygalacturonase (PG) based enzymes, at neutral pH (~7) and doses of 50, 100, and 150 ppm. Contact times were 18 and 36 h. Live/dead staining, epifluorescence microscopy measurements, and 5 μm thick cryo-sections of enzyme and physically treated biofouled membranes revealed that Subtilisin protease- and lipase-based enzymes at 100 ppm and 18 h contact time were optimal for removing most of the cells and proteins from the RO surface. Culturable cells inside the biofilm declined by more than five logs even at the lower dose (50 ppm) and shorter incubation period (18 h). Subtilisin protease- and lipase-based enzyme cleaning at 100 ppm and for 18 h contact time restored the hydrophobicity of the TFC RO surface to its virgin condition while physical cleaning alone resulted in a 50° increase in hydrophobicity. Moreover, at this optimum working condition, the Subtilisin protease- and lipase-based enzyme treatment of biofouled RO surface also restored the surface roughness measured with atomic force microscopy and the mass percentage of the chemical compositions on the TFC surface estimated with X-ray photoelectron spectroscopy to its virgin condition. This novel study will encourage the further development and application of enzymes to remove biofoulants on the RO surface without changing its surface properties.

  1. Enzymatic cleaning of biofouled thin-film composite reverse osmosis (RO) membrane operated in a biofilm membrane reactor.

    Science.gov (United States)

    Khan, Mohiuddin; Danielsen, Steffen; Johansen, Katja; Lorenz, Lindsey; Nelson, Sara; Camper, Anne

    2014-02-01

    Application of environmentally friendly enzymes to remove thin-film composite (TFC) reverse osmosis (RO) membrane biofoulants without changing the physico-chemical properties of the RO surface is a challenging and new concept. Eight enzymes from Novozyme A/S were tested using a commercially available biofouling-resistant TFC polyamide RO membrane (BW30, FilmTech Corporation, Dow Chemical Co.) without filtration in a rotating disk reactor system operated for 58 days. At the end of the operation, the accumulated biofoulants on the TFC RO surfaces were treated with the three best enzymes, Subtilisin protease and lipase; dextranase; and polygalacturonase (PG) based enzymes, at neutral pH (~7) and doses of 50, 100, and 150 ppm. Contact times were 18 and 36 h. Live/dead staining, epifluorescence microscopy measurements, and 5 μm thick cryo-sections of enzyme and physically treated biofouled membranes revealed that Subtilisin protease- and lipase-based enzymes at 100 ppm and 18 h contact time were optimal for removing most of the cells and proteins from the RO surface. Culturable cells inside the biofilm declined by more than five logs even at the lower dose (50 ppm) and shorter incubation period (18 h). Subtilisin protease- and lipase-based enzyme cleaning at 100 ppm and for 18 h contact time restored the hydrophobicity of the TFC RO surface to its virgin condition while physical cleaning alone resulted in a 50° increase in hydrophobicity. Moreover, at this optimum working condition, the Subtilisin protease- and lipase-based enzyme treatment of biofouled RO surface also restored the surface roughness measured with atomic force microscopy and the mass percentage of the chemical compositions on the TFC surface estimated with X-ray photoelectron spectroscopy to its virgin condition. This novel study will encourage the further development and application of enzymes to remove biofoulants on the RO surface without changing its surface properties. PMID:24329165

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  4. Membrane biofouling in a wastewater nitrification reactor: microbial succession from autotrophic colonization to heterotrophic domination

    KAUST Repository

    Lu, Huijie

    2015-10-22

    Membrane biofouling is a complex process that involves bacterial adhesion, extracellular polymeric substances (EPS) excretion and utilization, and species interactions. To obtain a better understanding of the microbial ecology of biofouling process, this study conducted rigorous, time-course analyses on the structure, EPS and microbial composition of the fouling layer developed on ultrafiltration membranes in a nitrification bioreactor. During a 14-day fouling event, three phases were determined according to the flux decline and microbial succession patterns. In Phase I (0-2 days), small sludge flocs in the bulk liquid were selectively attached on membrane surfaces, leading to the formation of similar EPS and microbial community composition as the early biofilms. Dominant populations in small flocs, e.g., Nitrosomonas, Nitrobacter, and Acinetobacter spp., were also the major initial colonizers on membranes. In Phase II (2-4 d), fouling layer structure, EPS composition, and bacterial community went through significant changes. Initial colonizers were replaced by fast-growing and metabolically versatile heterotrophs (e.g., unclassified Sphingobacteria). The declining EPS polysaccharide to protein (PS:PN) ratios could be correlated well with the increase in microbial community diversity. In Phase III (5-14 d), heterotrophs comprised over 90% of the community, whereas biofilm structure and EPS composition remained relatively stable. In all phases, AOB and NOB were constantly found within the top 40% of the fouling layer, with the maximum concentrations around 15% from the top. The overall microbial succession pattern from autotrophic colonization to heterotrophic domination implied that MBR biofouling could be alleviated by forming larger bacterial flocs in bioreactor suspension (reducing autotrophic colonization), and by designing more specific cleaning procedures targeting dominant heterotrophs during typical filtration cycles.

  5. Bacterial communities associated with biofouling materials used in bench-scale hydrocarbon bioremediation.

    Science.gov (United States)

    Al-Mailem, Dina; Kansour, Mayada; Radwan, Samir

    2015-03-01

    Biofouling material samples from the Arabian (Persian) Gulf, used as inocula in batch cultures, brought about crude oil and pure-hydrocarbon removal in a mineral medium. Without any added nitrogen fertilizers, the hydrocarbon-removal values were between about 10 and 50 %. Fertilization with NaNO3 alone or together with a mixture of the vitamins thiamine, pyridoxine, vitamin B12, biotin, riboflavin, and folic acid increased the hydrocarbon-removal values, to reach 90 %. Biofouling material samples harbored total bacteria in the magnitude of 10(7) cells g(-1), about 25 % of which were hydrocarbonoclastic. These numbers were enhanced by NaNO3 and vitamin amendment. The culture-independent analysis of the total bacterioflora revealed the predominance of the gammaproteobacterial genera Marinobacter, Acinetobacter, and Alcanivorax, the Flavobacteriia, Flavobacterium, Gaetbulibacter, and Owenweeksia, and the Alphaproteobacteria Tistrella, Zavarzinia, and others. Most of those bacteria are hydrocarbonoclastic. Culture-dependent analysis of hydrocarbonoclastic bacteria revealed that Marinobacter hydrocarbonoclasticus, Dietzia maris, and Gordonia bronchialis predominated in the fouling materials. In addition, each material had several more-specific hydrocarbonoclastic species, whose frequencies were enhanced by NaNO3 and vitamin fertilization. The same samples of fouling materials were used in four successive crude-oil-removal cycles without any dramatic loss of their hydrocarbon-removal potential nor of their associated hydrocarbonoclastic bacteria. In the fifth cycle, the oil-removal value was reduced by about 50 % in only one of the studied samples. This highlights how firmly biofouling materials were immobilizing the hydrocarbonoclastic bacteria.

  6. Membrane biofouling in a wastewater nitrification reactor: Microbial succession from autotrophic colonization to heterotrophic domination.

    Science.gov (United States)

    Lu, Huijie; Xue, Zheng; Saikaly, Pascal; Nunes, Suzana P; Bluver, Ted R; Liu, Wen-Tso

    2016-01-01

    Membrane biofouling is a complex process that involves bacterial adhesion, extracellular polymeric substances (EPS) excretion and utilization, and species interactions. To obtain a better understanding of the microbial ecology of biofouling process, this study conducted rigorous, time-course analyses on the structure, EPS and microbial composition of the fouling layer developed on ultrafiltration membranes in a nitrification bioreactor. During a 14-day fouling event, three phases were determined according to the flux decline and microbial succession patterns. In Phase I (0-2 days), small sludge flocs in the bulk liquid were selectively attached on membrane surfaces, leading to the formation of similar EPS and microbial community composition as the early biofilms. Dominant populations in small flocs, e.g., Nitrosomonas, Nitrobacter, and Acinetobacter spp., were also the major initial colonizers on membranes. In Phase II (2-4 d), fouling layer structure, EPS composition, and bacterial community went through significant changes. Initial colonizers were replaced by fast-growing and metabolically versatile heterotrophs (e.g., unclassified Sphingobacteria). The declining EPS polysaccharide to protein (PS:PN) ratios could be correlated well with the increase in microbial community diversity. In Phase III (5-14 d), heterotrophs comprised over 90% of the community, whereas biofilm structure and EPS composition remained relatively stable. In all phases, AOB and NOB were constantly found within the top 40% of the fouling layer, with the maximum concentrations around 15% from the top. The overall microbial succession pattern from autotrophic colonization to heterotrophic domination implied that MBR biofouling could be alleviated by forming larger bacterial flocs in bioreactor suspension (reducing autotrophic colonization), and by designing more specific cleaning procedures targeting dominant heterotrophs during typical filtration cycles.

  7. Impaired Performance of Pressure-Retarded Osmosis due to Irreversible Biofouling.

    Science.gov (United States)

    Bar-Zeev, Edo; Perreault, François; Straub, Anthony P; Elimelech, Menachem

    2015-11-01

    Next-generation pressure-retarded osmosis (PRO) approaches aim to harness the energy potential of streams with high salinity differences, such as wastewater effluent and seawater desalination plant brine. In this study, we evaluated biofouling propensity in PRO. Bench-scale experiments were carried out for 24 h using a model wastewater effluent feed solution and simulated seawater desalination brine pressurized to 24 bar. For biofouling tests, wastewater effluent was inoculated with Pseudomonas aeruginosa and artificial seawater desalination plant brine draw solution was seeded with Pseudoalteromonas atlantica. Our results indicate that biological growth in the feed wastewater stream channel severely fouled both the membrane support layer and feed spacer, resulting in ∼50% water flux decline. We also observed an increase in the pumping pressure required to force water through the spacer-filled feed channel, with pressure drop increasing from 6.4±0.8 bar m(-1) to 15.1±2.6 bar m(-1) due to spacer blockage from the developing biofilm. Neither the water flux decline nor the increased pressure drop in the feed channel could be reversed using a pressure-aided osmotic backwash. In contrast, biofouling in the seawater brine draw channel was negligible. Overall, the reduced performance due to water flux decline and increased pumping energy requirements from spacer blockage highlight the serious challenges of using high fouling potential feed sources in PRO, such as secondary wastewater effluent. We conclude that PRO power generation using wastewater effluent and seawater desalination plant brine may become possible only with rigorous pretreatment or new spacer and membrane designs.

  8. Structures and antifouling properties of low surface energy non-toxic antifouling coatings modified by nano-SiO2 powder

    Institute of Scientific and Technical Information of China (English)

    CHEN MeiLing; QU YuanYuan; YANG Li; GAO Hong

    2008-01-01

    Antifouling coatings are used to improve the speed and energy efficiency of ships by preventing or-ganisms, such as barnacles and weed, building up on the underwater hull and helping the ships movement through the water. Typically, marine coatings are tributyltin self-polishing copolymer paints containing toxic molecules called biocides. They have been the most successful in combating bio-fouling on ships, but their widespread use has caused severe pollution in the marine ecosystem. The low surface energy marine coating is an entirely non-toxic alternative, which reduces the adhesion strength of marine organisms, facilitating their hydrodynamic removal at high speeds. In this paper, the novel low surface energy non-toxic marine antifouling coatings were prepared with modified acrylic resin, nano-SiO2, and other pigments. The effects of nano-SiO2 on the surface structure and elastic modulus of coating films have been studied, and the seawater test has been carried out in the Dalian Bay. The results showed that micro-nano layered structures on the coating films and the lowest surface energy and elastic modulus could be obtained when an appropriate mass ratio of resin, nano-SiO2, and other pigments in coatings approached. The seawater exposure test has shown that the lower the sur-face energy and elastic modulus of coatings are, the less the marine biofouling adheres on the coating films.

  9. Biofouling of reverse-osmosis membranes during tertiary wastewater desalination: microbial community composition.

    Science.gov (United States)

    Al Ashhab, Ashraf; Herzberg, Moshe; Gillor, Osnat

    2014-03-01

    Reverse-osmosis (RO) desalination is frequently used for the production of high-quality water from tertiary treated wastewater (TTWW). However, the RO desalination process is often hampered by biofouling, including membrane conditioning, microbial adhesion, and biofilm growth. The vast majority of biofilm exploration concentrated on the role of bacteria in biofouling neglecting additional microbial contributors, i.e., fungi and archaea. To better understand the RO biofouling process, bacterial, archaeal and fungal diversity was characterized in a laboratory-scale RO desalination plant exploring the TTWW (RO feed), the RO membrane and the RO feed tube biofilms. We sequenced 77,400 fragments of the ribosome small subunit-encoding gene (16S and 18S rRNA) to identify the microbial community members in these matrices. Our results suggest that the bacterial, archaeal but not fungal community significantly differ from the RO membrane biofouling layer to the feedwater and tube biofilm (P < 0.01). Moreover, the RO membrane supported a more diverse community compared to the communities monitored in the feedwater and the biofilm attached to the RO feedwater tube. The tube biofilm was dominated by Actinobacteria (91.2 ± 4.6%), while the Proteobacteria phylum dominated the feedwater and RO membrane (at relative abundance of 92.3 ± 4.4% and 71.5 ± 8.3%, respectively), albeit comprising different members. The archaea communities were dominated by Crenarchaeota (53.0 ± 6.9%, 32.5 ± 7.2% and 69%, respectively) and Euryarchaeota (43.3 ± 6.3%, 23.2 ± 4.8% and 24%, respectively) in all three matrices, though the communities' composition differed. But the fungal communities composition was similar in all matrices, dominated by Ascomycota (97.6 ± 2.7%). Our results suggest that the RO membrane is a selective surface, supporting unique bacterial, and to a lesser extent archaeal communities, yet it does not select for a fungal community.

  10. Modeling the effect of spacers and biofouling on forward osmosis performance

    KAUST Repository

    Mosqueira Santillán, María José

    2014-11-01

    Currently, the most utilized desalination technology is reverse osmosis (RO), where a membrane is used as a physical barrier to separate the salts from the seawater, using high hydraulic pressure as driving force. A major problem in RO systems is biofouling, caused by severe growth of bacterial biofilms. Both, the need of an external energy input, as well as biofouling, impose a high cost on RO operation. Forward osmosis (FO) is an alternative membrane process that uses an osmotic pressure difference as driving force. FO uses a concentrated draw solution to generate high osmotic pressure, which extracts water across a semi permeable membrane from a feed solution. One of the main advantages of FO is the limited amount of external energy required to extract water from the feed solution. The objective of this research is the assessment of the impact of spacers, separating the membrane sheets, and biofouling on the FO system performance. This type of studies allow the optimization of membrane devices and operational conditions. For this, a two dimensional numerical model for FO systems was developed using computational fluid dynamics (CFD). This model allowed the evaluation of the impact of (i) spacers and (ii) biofilm, and (iii) the combined impact of spacers and biofilm on the performance of FO systems. The results obtained showed that the presence of spacers improved the performance of FO systems. Cavity configuration spacer gave the higher water flux across the membrane in clean systems; whereas for biofouled systems, the submerged configuration showed a better performance. In absence of spacers, the thickness or amount of biofilm is inversely proportional with the water flux. Furthermore, membrane surface coverage of the biofilm is more important than the amount of biofilm in terms of the impact on the performance. The numerical model can be adapted with other parameters (e.g. membrane and spacer thickness, feed and draw solution, solution concentration, etc.) to

  11. Surface modification strategies on mesoporous silica nanoparticles for anti-biofouling zwitterionic film grafting.

    Science.gov (United States)

    Khung, Yit Lung; Narducci, Dario

    2015-12-01

    In the past decade, zwitterionic-based anti-biofouling layers had gained much focus as a serious alternative to traditional polyhydrophilic films such as PEG. In the area of assembling silica nanoparticles with stealth properties, the incorporation of zwitterionic surface film remains fairly new but considering that silica nanoparticles had been widely demonstrated as useful biointerfacing nanodevice, zwitterionic film grafting on silica nanoparticle holds much potential in the future. This review will discuss on the conceivable functional chemistry approaches, some of which are potentially suitable for the assembly of such stealth systems.

  12. Fouling-resistant polymer brush coatings

    KAUST Repository

    Thérien-Aubin, Héloïse

    2011-11-01

    A major problem to be addressed with thin composite films used in processes such as coatings or water purification is the biofouling of the surface. To address this problem in a model system, functionalized polyaramide membranes containing an atom transfer radical polymerization (ATRP) initiator were synthesized as a versatile approach to easily modify the surface properties of the polyaramide. Poly(methacrylic acid) brushes were grown using surface initiated ATRP followed by the functionalization of the poly(methacrylic acid) brushes with different side-chains chosen to reduce adhesion between the membrane and foulant. The relation between membrane fouling and the physicochemical properties of the surface was investigated in detail. © 2011 Elsevier Ltd. All rights reserved.

  13. Interrogating chemical variation via layer-by-layer SERS during biofouling and cleaning of nanofiltration membranes with further investigations into cleaning efficiency.

    Science.gov (United States)

    Cui, Li; Chen, Pengyu; Zhang, Bifeng; Zhang, Dayi; Li, Junyi; Martin, Francis L; Zhang, Kaisong

    2015-12-15

    Periodic chemical cleaning is an essential step to maintain nanofiltration (NF) membrane performance and mitigate biofouling, a major impediment in high-quality water reclamation from wastewater effluent. To target the important issue of how to clean and control biofouling more efficiently, this study developed surface-enhanced Raman spectroscopy (SERS) as a layer-by-layer tool to interrogate the chemical variations during both biofouling and cleaning processes. The fact that SERS only reveals information on the surface composition of biofouling directly exposed to cleaning reagents makes it ideal for evaluating cleaning processes and efficiency. SERS features were highly distinct and consistent with different biofouling stages (bacterial adhesion, rapid growth, mature and aged biofilm). Cleaning was performed on two levels of biofouling after 18 h (rapid growth of biofilm) and 48 h (aged biofilm) development. An opposing profile of SERS bands between biofouling and cleaning was observed and this suggests a layer-by-layer cleaning mode. In addition, further dynamic biochemical and infrastructural changes were demonstrated to occur in the more severe 48-h biofouling, resulting in the easier removal of sessile cells from the NF membrane. Biofouling substance-dependent cleaning efficiency was also evaluated using the surfactant sodium dodecyl sulfate (SDS). SDS appeared more efficient in cleaning lipid than polysaccharide and DNA. Protein and DNA were the predominant residual substances (irreversible fouling) on NF membrane leading to permanent flux loss. The chemical information revealed by layer-by-layer SERS will lend new insights into the optimization of cleaning reagents and protocols for practical membrane processes. PMID:26433006

  14. Interrogating chemical variation via layer-by-layer SERS during biofouling and cleaning of nanofiltration membranes with further investigations into cleaning efficiency.

    Science.gov (United States)

    Cui, Li; Chen, Pengyu; Zhang, Bifeng; Zhang, Dayi; Li, Junyi; Martin, Francis L; Zhang, Kaisong

    2015-12-15

    Periodic chemical cleaning is an essential step to maintain nanofiltration (NF) membrane performance and mitigate biofouling, a major impediment in high-quality water reclamation from wastewater effluent. To target the important issue of how to clean and control biofouling more efficiently, this study developed surface-enhanced Raman spectroscopy (SERS) as a layer-by-layer tool to interrogate the chemical variations during both biofouling and cleaning processes. The fact that SERS only reveals information on the surface composition of biofouling directly exposed to cleaning reagents makes it ideal for evaluating cleaning processes and efficiency. SERS features were highly distinct and consistent with different biofouling stages (bacterial adhesion, rapid growth, mature and aged biofilm). Cleaning was performed on two levels of biofouling after 18 h (rapid growth of biofilm) and 48 h (aged biofilm) development. An opposing profile of SERS bands between biofouling and cleaning was observed and this suggests a layer-by-layer cleaning mode. In addition, further dynamic biochemical and infrastructural changes were demonstrated to occur in the more severe 48-h biofouling, resulting in the easier removal of sessile cells from the NF membrane. Biofouling substance-dependent cleaning efficiency was also evaluated using the surfactant sodium dodecyl sulfate (SDS). SDS appeared more efficient in cleaning lipid than polysaccharide and DNA. Protein and DNA were the predominant residual substances (irreversible fouling) on NF membrane leading to permanent flux loss. The chemical information revealed by layer-by-layer SERS will lend new insights into the optimization of cleaning reagents and protocols for practical membrane processes.

  15. Biofouling management in the cooling circuit of a power industry using electrochemical process

    International Nuclear Information System (INIS)

    Biofouling is one of the major issues in the power industry using seawater for cooling and other purposes. Presence of biological organisms such as bacteria and algae that could foul pipes and expensive equipment need to be managed from economical and safety point of view. Generally, the biofouling problem is aggravated in hot climate regions. Various means of disinfection processes are available for this purpose, such as chlorination, UV or ozone. In the present study electrochemical technology for the production of sodium hypochlorite was evaluated for onsite disinfection of seawater for applications in a nuclear power industry. A continues flow laboratory scale experimental setup was fabricated and influence of various operating parameters such as electrode material, applied current density, power consumption, surface area of electrode and interelectrode spacing were evaluated. It was found that efficiency of the electrochemical disinfection process was strongly dependent on these studied operating parameters. It was concluded that the production of sodium hypochlorite on site using an electrochemical process is a feasible and promising option for the power industry using seawater as cooling and/or process water. An optimum design of the electrochemical cell was also suggested. (author)

  16. Combined biofouling and scaling in membrane feed channels: a new modeling approach.

    Science.gov (United States)

    Radu, A I; Bergwerff, L; van Loosdrecht, M C M; Picioreanu, C

    2015-01-01

    A mathematical model was developed for combined fouling due to biofilms and mineral precipitates in membrane feed channels with spacers. Finite element simulation of flow and solute transport in two-dimensional geometries was coupled with a particle-based approach for the development of a composite (cells and crystals) foulant layer. Three fouling scenarios were compared: biofouling only, scaling only and combined fouling. Combined fouling causes a quicker flux decline than the summed flux deterioration when scaling and biofouling act independently. The model results indicate that the presence of biofilms leads to more mineral formation due to: (1) an enhanced degree of saturation for salts next to the membrane and within the biofilm; and (2) more available surface for nucleation to occur. The impact of biofilm in accelerating gypsum precipitation depends on the composition of the feed water (eg the presence of NaCl) and the kinetics of crystal nucleation and growth. Interactions between flow, solute transport and biofilm-induced mineralization are discussed.

  17. Impacts of hydrophilic colanic acid on bacterial attachment to microfiltration membranes and subsequent membrane biofouling.

    Science.gov (United States)

    Yoshida, Keitaro; Tashiro, Yosuke; May, Thithiwat; Okabe, Satoshi

    2015-06-01

    In order to examine the interactions between physicochemical properties of specific extracellular polymeric substances (EPS) and membrane biofouling, we investigated the impacts of hydrophilic colanic acid, as a model extracellular polysaccharide component, on initial bacterial attachment to different microfiltration (MF) membranes and membrane biofouling by using Escherichia coli strains producing different amounts of colanic acid. In a newly designed microtiter plate assay, the bacterial attachment by an E. coli strain RcsF(+), which produces massive amounts of colanic acid, decreased only to a hydrophobic membrane because the colanic acid made cell surfaces more hydrophilic, resulting in low cell attachment to hydrophobic membranes. The bench-scale cross-flow filtration tests followed by filtration resistance measurement revealed that RcsF(+) caused severe irreversible membrane fouling (i.e., pore-clogging), whereas less extracellular polysaccharide-producing strains caused moderate but reversible fouling to all membranes used in this study. Further cross-flow filtration tests indicated that colanic acid liberated in the bulk phase could rapidly penetrate pre-accumulated biomass layers (i.e., biofilms) and then directly clogged membrane pores. These results indicate that colanic acid, a hydrophilic extracellular polysaccharide, and possible polysaccharides with similar characteristics with colanic acid are considered as a major cause of severe irreversible membrane fouling (i.e., pore-clogging) regardless of biofilm formation (dynamic membrane).

  18. Biofouling and the continuous monitoring of underwater light from a seagrass perspective

    Science.gov (United States)

    Onuf, C.P.

    2006-01-01

    For more than a decade, inexpensive electronic instruments have made continuous underwater light monitoring an integral part of many seagrass studies. Although biofouling, if not controlled, compromises the utility of the record. A year-long assessment of the time course of sensor fouling, in the Laguna Madre of Texas established that light transmitted through the fouling layer after 2 wk of exposure exceeded 90% except for a 6-8 wk period in May and June. On that basis, a 2-wk interval was chosen for routine servicing. Subsequent monitoring proved this choice to be grossly in error. The period of sub-90% transmittance after 2 wk extended to 4-6 mo annually over the next 3 yr. Fouling was strongly correlated with temperature, ambient light, and year. Since an algal bloom of 7-yr duration finally waned during this study, increased ambient light seemed most likely to explain increased fouling later in the study. The explanatory value of light was less than temperature or year in multiple regression, requiring some other explanation of the date effect than change in ambient light. Allelopathic and suspension-feeding depressant effects of the brown tide are offered as the most likely cause of unusually low fouling in the first year. Biofouling was so unpredictable and rapid in this study that at least weekly maintenance would be required to assure reliability of the light monitoring record. ?? 2006 Estuarine Research Federation.

  19. It's a wrap: encapsulation as a management tool for marine biofouling.

    Science.gov (United States)

    Atalah, Javier; Brook, Rosemary; Cahill, Patrick; Fletcher, Lauren M; Hopkins, Grant A

    2016-01-01

    Encapsulation of fouled structures is an effective tool for countering incursions by non-indigenous biofoulers. However, guidelines for the implementation of encapsulation treatments are yet to be established. This study evaluated the effects of temperature, biomass, community composition, treatment duration and the biocide acetic acid on biofoulers. In laboratory trials using the model organisms Ciona spp. and Mytilus galloprovincialis, increasing the temperature or biomass speeded up the development of a toxic environment. Total mortality for Ciona spp. occurred within 72 and 24 h at 10 and 19°C, respectively. M. galloprovincialis survived up to 18 days, with high biomass increasing mortality at 10°C only. In a field study, three-month-old and four-year-old communities were encapsulated with and without acetic acid. Mortality took up to 10 days for communities encapsulated without acetic acid, compared to 48 h with acetic acid. The insights gained from this study will be useful in developing standardised encapsulation protocols.

  20. Preparation, anti-biofouling and drag-reduction properties of a biomimetic shark skin surface

    Directory of Open Access Journals (Sweden)

    Xia Pu

    2016-04-01

    Full Text Available Shark skin surfaces show non-smoothness characteristics due to the presence of a riblet structure. In this study, biomimetic shark skin was prepared by using the polydimethylsiloxane (PDMS-embedded elastomeric stamping (PEES method. Scanning electron microscopy (SEM was used to examine the surface microstructure and fine structure of shark skin and biomimetic shark skin. To analyse the hydrophobic mechanism of the shark skin surface microstructure, the effect of biomimetic shark skin surface microstructure on surface wettability was evaluated by recording water contact angle. Additionally, protein adhesion experiments and anti-algae adhesion performance testing experiments were used to investigate and evaluate the anti-biofouling properties of the surface microstructure of biomimetic shark skin. The recorded values of the water contact angle of differently microstructured surfaces revealed that specific microstructures have certain effects on surface wettability. The anti-biofouling properties of the biomimetic shark skin surface with microstructures were superior to a smooth surface using the same polymers as substrates. Moreover, the air layer fixed on the surface of the biomimetic shark skin was found to play a key role in their antibiont adhesion property. An experiment into drag reduction was also conducted. Based on the experimental results, the microstructured surface of the prepared biomimetic shark skin played a significant role in reducing drag. The maximum of drag reduction rate is 12.5%, which is higher than the corresponding maximum drag reduction rate of membrane material with a smooth surface.

  1. Characterization of biofouling in a lab-scale forward osmosis membrane bioreactor (FOMBR).

    Science.gov (United States)

    Zhang, Qiaoyun; Jie, Yap Wei; Loong, Winson Lay Chee; Zhang, Jinsong; Fane, Anthony G; Kjelleberg, Staffan; Rice, Scott A; McDougald, Diane

    2014-07-01

    Forward osmosis membrane bioreactors (FOMBR) provide high quality permeate, however the propensity for membrane biofouling in FOMBRs is unknown. Here, FOMBRs were operated under high and low aeration and the membrane-associated biofilms were characterized by confocal laser scanning microscopy (CLSM) and rRNA gene-tagged pyrosequencing. CLSM images revealed that there was little biofilm formed under high aeration, while thick biofilms were observed on the membranes operated under low aeration. The diversity and richness of bacterial and archaeal communities as assessed by pyrosequencing varied under high and low aeration. The composition of the bacterial suspended sludge communities and the sessile biomass on the membrane surface, as assessed by non-metric multidimensional scaling, was significantly different under high aeration, but was more similar under low aeration. SIMPER analysis indicated that Pseudomonas, Aeromonas and Fluviicola preferentially attached to the membrane. The results presented here provide a comprehensive understanding of membrane biofouling in FOMBRs, which is essential for the development of effective control strategies.

  2. Amplified recruitment pressure of biofouling organisms in commercial salmon farms: potential causes and implications for farm management.

    Science.gov (United States)

    Bloecher, Nina; Floerl, Oliver; Sunde, Leif Magne

    2015-01-01

    The development of biofouling on finfish aquaculture farms presents challenges for the industry, but the factors underlying nuisance growths are still not well understood. Artificial settlement surfaces were used to examine two possible explanations for high rates of biofouling in Norwegian salmon farms: (1) increased propagule release during net cleaning operations, resulting in elevated recruitment rates; and (2) potential reservoir effects of farm surfaces. The presence of salmon farms was associated with consistently and substantially (up to 49-fold) elevated recruitment rates. Temporal patterns of recruitment were not driven by net cleaning. Resident populations of biofouling organisms were encountered on all submerged farm surfaces. Calculations indicate that a resident population of the hydroid Ectopleura larynx, a major biofouling species, could release between 0.3 × 10(9) and 4.7 × 10(9) larvae per farm annually. Such resident populations could form propagule reservoirs and be one explanation for the elevated recruitment pressure at salmon farms.

  3. Electrochemical detection of hydrogen peroxide on platinum-containing tetrahedral amorphous carbon sensors and evaluation of their biofouling properties.

    Science.gov (United States)

    Tujunen, Noora; Kaivosoja, Emilia; Protopopova, Vera; Valle-Delgado, Juan José; Österberg, Monika; Koskinen, Jari; Laurila, Tomi

    2015-10-01

    Hydrogen peroxide is the product of various enzymatic reactions, and is thus typically utilized as the analyte in biosensors. However, its detection with conventional materials, such as noble metals or glassy carbon, is often hindered by slow kinetics and biofouling of the electrode. In this study electrochemical properties and suitability to peroxide detection as well as ability to resist biofouling of Pt-doped ta-C samples were evaluated. Pure ta-C and pure Pt were used as references. According to the results presented here it is proposed that combining ta-C with Pt results in good electrocatalytic activity towards H2O2 oxidation with better tolerance towards aqueous environment mimicking physiological conditions compared to pure Pt. In biofouling experiments, however, both the hybrid material and Pt were almost completely blocked after immersion in protein-containing solutions and did not produce any peaks for ferrocenemethanol oxidation or reduction. On the contrary, it was still possible to obtain clear peaks for H2O2 oxidation with them after similar treatment. Moreover, quartz crystal microbalance experiment showed less protein adsorption on the hybrid sample compared to Pt which is also supported by the electrochemical biofouling experiments for H2O2 detection.

  4. Inhibition of coated pit formation in Hep2 cells blocks the cytotoxicity of diphtheria toxin but not that of ricin toxin

    OpenAIRE

    1985-01-01

    It has been recently shown (Larkin, J. M., M. S. Brown, J. L. Goldstein, and R. G. W. Anderson, 1983, Cell, 33:273-285) that after a hypotonic shock followed by incubation in a K+-free medium, human fibroblasts arrest their coated pit formation and therefore arrest receptor-mediated endocytosis of low density lipoprotein. We have used this technique to study the endocytosis of transferrin, diphtheria toxin, and ricin toxin by three cell lines (Vero, Wi38/SV40, and Hep2 cells). Only Hep2 cells...

  5. Self-cleaning Metal Organic Framework (MOF) based ultra filtration membranes - A solution to bio-fouling in membrane separation processes

    OpenAIRE

    Prince, J. A.; Bhuvana, S.; Anbharasi, V.; Ayyanar, N.; Boodhoo, K. V. K.; Singh, G.

    2014-01-01

    Bio-fouling is a serious problem in many membrane-based separation processes for water and wastewater treatment. Current state of the art methods to overcome this are to modify the membranes with either hydrophilic additives or with an antibacterial compound. In this study, we propose and practise a novel concept to prevent bio-fouling by developing a killing and self-cleaning membrane surface incorporating antibacterial silver nanoparticles and highly hydrophilic negatively charged carboxyli...

  6. Use of ceragenins to create novel biofouling resistant water-treatment membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael R.; Altman, Susan Jeanne; Feng, Yanshu (Brigham Young University, Provo, UT); Savage, Paul B. (Brigham Young University, Provo, UT); Pollard, Jacob (Brigham Young University, Provo, UT); Sanchez, Andres L. (LMATA, Albuquerque, NM); Fellows, Benjamin D.; Jones, Howland D. T.; McGrath, Lucas K. (LMATA, Albuquerque, NM)

    2008-12-01

    Scoping studies have demonstrated that ceragenins, when linked to water-treatment membranes have the potential to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced molecules that mimic antimicrobial peptides. Evidence includes measurements of CSA-13 prohibiting the growth of and killing planktonic Pseudomonas fluorescens. In addition, imaging of biofilms that were in contact of a ceragenin showed more dead cells relative to live cells than in a biofilm that had not been treated with a ceragenin. This work has demonstrated that ceragenins can be attached to polyamide reverse osmosis (RO) membranes, though work needs to improve the uniformity of the attachment. Finally, methods have been developed to use hyperspectral imaging with multivariate curve resolution to view ceragenins attached to the RO membrane. Future work will be conducted to better attach the ceragenin to the RO membranes and more completely test the biocidal effectiveness of the ceragenins on the membranes.

  7. Metabarcoding improves detection of eukaryotes from early biofouling communities: implications for pest monitoring and pathway management.

    Science.gov (United States)

    Zaiko, Anastasija; Schimanski, Kate; Pochon, Xavier; Hopkins, Grant A; Goldstien, Sharyn; Floerl, Oliver; Wood, Susanna A

    2016-07-01

    In this experimental study the patterns in early marine biofouling communities and possible implications for surveillance and environmental management were explored using metabarcoding, viz. 18S ribosomal RNA gene barcoding in combination with high-throughput sequencing. The community structure of eukaryotic assemblages and the patterns of initial succession were assessed from settlement plates deployed in a busy port for one, five and 15 days. The metabarcoding results were verified with traditional morphological identification of taxa from selected experimental plates. Metabarcoding analysis identified > 400 taxa at a comparatively low taxonomic level and morphological analysis resulted in the detection of 25 taxa at varying levels of resolution. Despite the differences in resolution, data from both methods were consistent at high taxonomic levels and similar patterns in community shifts were observed. A high percentage of sequences belonging to genera known to contain non-indigenous species (NIS) were detected after exposure for only one day.

  8. Metabarcoding improves detection of eukaryotes from early biofouling communities: implications for pest monitoring and pathway management.

    Science.gov (United States)

    Zaiko, Anastasija; Schimanski, Kate; Pochon, Xavier; Hopkins, Grant A; Goldstien, Sharyn; Floerl, Oliver; Wood, Susanna A

    2016-07-01

    In this experimental study the patterns in early marine biofouling communities and possible implications for surveillance and environmental management were explored using metabarcoding, viz. 18S ribosomal RNA gene barcoding in combination with high-throughput sequencing. The community structure of eukaryotic assemblages and the patterns of initial succession were assessed from settlement plates deployed in a busy port for one, five and 15 days. The metabarcoding results were verified with traditional morphological identification of taxa from selected experimental plates. Metabarcoding analysis identified > 400 taxa at a comparatively low taxonomic level and morphological analysis resulted in the detection of 25 taxa at varying levels of resolution. Despite the differences in resolution, data from both methods were consistent at high taxonomic levels and similar patterns in community shifts were observed. A high percentage of sequences belonging to genera known to contain non-indigenous species (NIS) were detected after exposure for only one day. PMID:27212415

  9. Membrane biofouling characterization: effects of sample preparation procedures on biofilm structure and the microbial community.

    Science.gov (United States)

    Xue, Zheng; Lu, Huijie; Liu, Wen-Tso

    2014-01-01

    Ensuring the quality and reproducibility of results from biofilm structure and microbial community analysis is essential to membrane biofouling studies. This study evaluated the impacts of three sample preparation factors (ie number of buffer rinses, storage time at 4°C, and DNA extraction method) on the downstream analysis of nitrifying biofilms grown on ultrafiltration membranes. Both rinse and storage affected biofilm structure, as suggested by their strong correlation with total biovolume, biofilm thickness, roughness and the spatial distribution of EPS. Significant variations in DNA yields and microbial community diversity were also observed among samples treated by different rinses, storage and DNA extraction methods. For the tested biofilms, two rinses, no storage and DNA extraction with both mechanical and chemical cell lysis from attached biofilm were the optimal sample preparation procedures for obtaining accurate information about biofilm structure, EPS distribution and the microbial community.

  10. Mitigation of biofouling using electromagnetic fields in tubular heat exchangers-condensers cooled by seawater.

    Science.gov (United States)

    Trueba, Alfredo; García, Sergio; Otero, Félix M

    2014-01-01

    Electromagnetic field (EMF) treatment is presented as an alternative physical treatment for the mitigation of biofouling adhered to the tubes of a heat exchanger-condenser cooled by seawater. During an experimental phase, a fouling biofilm was allowed to grow until experimental variables indicated that its growth had stabilised. Subsequently, EMF treatment was applied to seawater to eliminate the biofilm and to maintain the achieved cleanliness. The results showed that EMFs precipitated ions dissolved in the seawater. As a consequence of the application of EMFs, erosion altered the intermolecular bonding of extracellular polymers, causing the destruction of the biofilm matrix and its detachment from the inner surface of the heat exchanger-condenser tubes. This detachment led to the partial removal of a mature biofilm and a partial recovery of the efficiency lost in the heat transfer process by using a physical treatment that is harmless to the marine environment.

  11. Superhydrophobic PVDF and PVDF-HFP nanofibrous mats with antibacterial and anti-biofouling properties

    Science.gov (United States)

    Spasova, M.; Manolova, N.; Markova, N.; Rashkov, I.

    2016-02-01

    Superhydrophobic nanofibrous materials of poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) were prepared by one-pot electrospinning technique. The mats were decorated with ZnO nanoparticles with silanized surface and a model drug - 5-chloro-8-hydroxyquinolinol (5Cl8HQ). The obtained hybrid nanofibrous materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle measurements, mechanical and microbiological tests. The results showed that the incorporation of ZnO nanoparticles into PVDF and PVDF-HFP nanofibers increased the hydrophobicity (contact angle 152°), improved the thermal stability and imparted to the nanofibrous materials anti-adhesive and antimicrobial properties. The mats containing the model drug possessed antibacterial activity against Escherichia coli and Staphylococcus aureus. The results suggested that the obtained hybrid mats could find potential biomedical applications requiring antibacterial and anti-biofouling properties.

  12. MARINE BIOFOULING IN OFFSHORE AREAS SOUTH OF HAINAN ISLAND, NORTHERN SOUTH CHINA SEA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This study on the characteristics of fouling communities in offshore areas south of Hainan Island, northern South China Sea, was conducted at four sites there. At each station, test panels on iron frames were hung on the mooring system at different depths. Data on biofouling were mainly obtained by examination of the fouled test panels. Organisms attached to buoys and anchors were scraped off and examined also. The results showed that the thickness and biomass of marine growth that increased the fluid loading on offshore installations depended to a large extent on hard foulers, i.e. mollusks and acorn barnacles. Algae, hydroids, stalked barnacles and bryozoans were important fouling species. The occurrence frequency and biomass of acorn barnacles decreased with increasing distance from the shore.

  13. Biofouling on polymeric heat exchanger surfaces with E. coli and native biofilms.

    Science.gov (United States)

    Pohl, S; Madzgalla, M; Manz, W; Bart, H J

    2015-01-01

    The biofouling affinity of different polymeric surfaces (polypropylene, polysulfone, polyethylene terephthalate, and polyether ether ketone) in comparison to stainless steel (SS) was studied for the model bacterium Escherichia coli K12 DSM 498 and native biofilms originating from Rhine water. The biofilm mass deposited on the polymer surfaces was minimized by several magnitudes compared to SS. The cell count and the accumulated biomass of E. coli on the polymer surfaces showed an opposing linear trend. The promising low biofilm formation on the polymers is attributed to the combination of inherent surface properties (roughness, surface energy and hydrophobicity) when compared to SS. The fouling characteristics of E. coli biofilms show good conformity with the more complex native biofilms investigated. The results can be utilized for the development of new polymer heat exchangers when using untreated river water as coolant or for other processes needing antifouling materials.

  14. Cleaning efficacy of hydroxypropyl-beta-cyclodextrin for biofouling reduction on reverse osmosis membranes.

    Science.gov (United States)

    Alayande, Abayomi Babatunde; Kim, Lan Hee; Kim, In S

    2016-01-01

    In this study, an environmentally friendly compound, hydroxypropyl-beta-cyclodextrin (HP-β-CD) was applied to clean reverse osmosis (RO) membranes fouled by microorganisms. The cleaning with HP-β-CD removed the biofilm and resulted in a flux recovery ratio (FRR) of 102%. As cleaning efficiency is sometimes difficult to determine using flux recovery data alone, attached bacterial cells and extracellular polymeric substances (EPS) were quantified after cleaning the biofouled membrane with HP-β-CD. Membrane surface characterization using scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) and atomic force microscopy (AFM) confirmed the effectiveness of HP-β-CD in removal of biofilm from the RO membrane surface. Finally, a comparative study was performed to investigate the competitiveness of HP-β-CD with other known cleaning agents such as sodium dodecyl sulfate (SDS), ethylenediaminetetraacetic acid (EDTA), Tween 20, rhamnolipid, nisin, and surfactin. In all cases, HP-β-CD was superior.

  15. Membrane bioreactor wastewater treatment plants reveal diverse yeast and protist communities of potential significance in biofouling.

    Science.gov (United States)

    Liébana, Raquel; Arregui, Lucía; Belda, Ignacio; Gamella, Luis; Santos, Antonio; Marquina, Domingo; Serrano, Susana

    2015-01-01

    The yeast community was studied in a municipal full-scale membrane bioreactor wastewater treatment plant (MBR-WWTP). The unexpectedly high diversity of yeasts indicated that the activated sludge formed a suitable environment for them to proliferate, with cellular concentrations of 2.2 ± 0.8 × 10(3) CFU ml(-1). Sixteen species of seven genera were present in the biological reactor, with Ascomycetes being the most prevalent group (93%). Most isolates were able to grow in a synthetic wastewater medium, adhere to polyethylene surfaces, and develop biofilms of variable complexity. The relationship between yeast populations and the protists in the MBR-WWTP was also studied, revealing that some protist species preyed on and ingested yeasts. These results suggest that yeast populations may play a role in the food web of a WWTP and, to some extent, contribute to membrane biofouling in MBR systems.

  16. Use of ceregenins to create novel biofouling resistant water water-treatment membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Kirk, Matthew F.; Jones, Howland D. T.; Feng, Yanshu; McGrath, Lucas K.; Altman, Susan Jeanne; Pollard, Jacob; Hibbs, Michael R.; Savage, Paul B.

    2010-05-01

    Scoping studies have demonstrated that ceragenins, when linked to water-treatment membranes have the potential to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced molecules that mimic antimicrobial peptides. Evidence includes measurements of CSA-13 prohibiting the growth of and killing planktonic Pseudomonas fluorescens. In addition, imaging of biofilms that were in contact of a ceragenin showed more dead cells relative to live cells than in a biofilm that had not been treated with a ceragenin. This work has demonstrated that ceragenins can be attached to polyamide reverse osmosis (RO) membranes, though work needs to improve the uniformity of the attachment. Finally, methods have been developed to use hyperspectral imaging with multivariate curve resolution to view ceragenins attached to the RO membrane. Future work will be conducted to better attach the ceragenin to the RO membranes and more completely test the biocidal effectiveness of the ceragenins on the membranes.

  17. The effect of feed salinity on the biofouling dynamics of seawater desalination.

    Science.gov (United States)

    Yang, Hui-Ling; Pan, Jill R; Huang, Chihpin; Lin, Justin Chun-Te

    2011-05-01

    A persistent cell labeling dye and a novel microbial counting method were used to explore the effects of salinity on a microbial population in a reverse osmosis (RO) desalination system, and these clearly distinguished microbial cell multiplication from cell adherence. The results indicated that microbial multiplication is more active at the front of a seawater RO pressure vessel, while adhesion dominates the back of the vessel. A severe reduction in RO permeate flux and total dissolved solid (TDS) rejection were detected at low salinity, attributed to marked cell multiplication and release of extracellular polymeric substances, whilst a relatively stable flux was observed at medium and high salinity. The results from PCR-DGGE revealed the variation in microbial species distribution on the membrane with salinity. The results imply the critical role of membrane modification in biofouling mitigation in the desalination process.

  18. Membrane biofouling characterization: effects of sample preparation procedures on biofilm structure and the microbial community

    KAUST Repository

    Xue, Zheng

    2014-07-15

    Ensuring the quality and reproducibility of results from biofilm structure and microbial community analysis is essential to membrane biofouling studies. This study evaluated the impacts of three sample preparation factors (ie number of buffer rinses, storage time at 4°C, and DNA extraction method) on the downstream analysis of nitrifying biofilms grown on ultrafiltration membranes. Both rinse and storage affected biofilm structure, as suggested by their strong correlation with total biovolume, biofilm thickness, roughness and the spatial distribution of EPS. Significant variations in DNA yields and microbial community diversity were also observed among samples treated by different rinses, storage and DNA extraction methods. For the tested biofilms, two rinses, no storage and DNA extraction with both mechanical and chemical cell lysis from attached biofilm were the optimal sample preparation procedures for obtaining accurate information about biofilm structure, EPS distribution and the microbial community. © 2014 © 2014 Taylor & Francis.

  19. Biofouling on polymeric heat exchanger surfaces with E. coli and native biofilms.

    Science.gov (United States)

    Pohl, S; Madzgalla, M; Manz, W; Bart, H J

    2015-01-01

    The biofouling affinity of different polymeric surfaces (polypropylene, polysulfone, polyethylene terephthalate, and polyether ether ketone) in comparison to stainless steel (SS) was studied for the model bacterium Escherichia coli K12 DSM 498 and native biofilms originating from Rhine water. The biofilm mass deposited on the polymer surfaces was minimized by several magnitudes compared to SS. The cell count and the accumulated biomass of E. coli on the polymer surfaces showed an opposing linear trend. The promising low biofilm formation on the polymers is attributed to the combination of inherent surface properties (roughness, surface energy and hydrophobicity) when compared to SS. The fouling characteristics of E. coli biofilms show good conformity with the more complex native biofilms investigated. The results can be utilized for the development of new polymer heat exchangers when using untreated river water as coolant or for other processes needing antifouling materials. PMID:26479780

  20. Mitigation of biofouling using electromagnetic fields in tubular heat exchangers-condensers cooled by seawater.

    Science.gov (United States)

    Trueba, Alfredo; García, Sergio; Otero, Félix M

    2014-01-01

    Electromagnetic field (EMF) treatment is presented as an alternative physical treatment for the mitigation of biofouling adhered to the tubes of a heat exchanger-condenser cooled by seawater. During an experimental phase, a fouling biofilm was allowed to grow until experimental variables indicated that its growth had stabilised. Subsequently, EMF treatment was applied to seawater to eliminate the biofilm and to maintain the achieved cleanliness. The results showed that EMFs precipitated ions dissolved in the seawater. As a consequence of the application of EMFs, erosion altered the intermolecular bonding of extracellular polymers, causing the destruction of the biofilm matrix and its detachment from the inner surface of the heat exchanger-condenser tubes. This detachment led to the partial removal of a mature biofilm and a partial recovery of the efficiency lost in the heat transfer process by using a physical treatment that is harmless to the marine environment. PMID:24266611

  1. Surface modification of reverse osmosis desalination membranes by thin-film coatings deposited by initiated chemical vapor deposition

    International Nuclear Information System (INIS)

    Thin-film polymeric reverse osmosis membranes, due to their high permeation rates and good salt rejection capabilities, are widely used for seawater desalination. However, these membranes are prone to biofouling, which affects their performance and efficiency. In this work, we report a method to modify the membrane surface without damaging the active layer or significantly affecting the performance of the membrane. Amphiphilic copolymer films of hydrophilic hydroxyethylmethacrylate and hydrophobic perfluorodecylacrylate (PFA) were synthesized and deposited on commercial RO membranes using an initiated chemical vapor deposition technique which is a polymer deposition technique that involves free-radical polymerization initiated by gas-phase radicals. Relevant surface characteristics such as hydrophilicity and roughness could be systematically controlled by varying the polymer chemistry. Increasing the hydrophobic PFA content in the films leads to an increase in the surface roughness and hydrophobicity. Furthermore, the surface morphology studies performed using the atomic force microscopy show that as the thickness of the coating increases average surface roughness increases. Using this knowledge, the coating thickness and chemistry were optimized to achieve high permeate flux and to reduce cell attachment. Results of the static bacterial adhesion tests show that the attachment of bacterial cells is significantly reduced on the coated membranes. - Highlights: • Thin films are deposited on reverse osmosis membranes. • Amphiphilic thin films are resistant to protein attachment. • The permeation performance of the membranes is not affected by the coating. • The thin film coatings delayed the biofouling

  2. Surface modification of reverse osmosis desalination membranes by thin-film coatings deposited by initiated chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ozaydin-Ince, Gozde, E-mail: gozdeince@sabanciuniv.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Matin, Asif, E-mail: amatin@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khan, Zafarullah, E-mail: zukhan@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Zaidi, S.M. Javaid, E-mail: zaidismj@kfupm.edu.sa [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Gleason, Karen K., E-mail: kkgleasn@mit.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-07-31

    Thin-film polymeric reverse osmosis membranes, due to their high permeation rates and good salt rejection capabilities, are widely used for seawater desalination. However, these membranes are prone to biofouling, which affects their performance and efficiency. In this work, we report a method to modify the membrane surface without damaging the active layer or significantly affecting the performance of the membrane. Amphiphilic copolymer films of hydrophilic hydroxyethylmethacrylate and hydrophobic perfluorodecylacrylate (PFA) were synthesized and deposited on commercial RO membranes using an initiated chemical vapor deposition technique which is a polymer deposition technique that involves free-radical polymerization initiated by gas-phase radicals. Relevant surface characteristics such as hydrophilicity and roughness could be systematically controlled by varying the polymer chemistry. Increasing the hydrophobic PFA content in the films leads to an increase in the surface roughness and hydrophobicity. Furthermore, the surface morphology studies performed using the atomic force microscopy show that as the thickness of the coating increases average surface roughness increases. Using this knowledge, the coating thickness and chemistry were optimized to achieve high permeate flux and to reduce cell attachment. Results of the static bacterial adhesion tests show that the attachment of bacterial cells is significantly reduced on the coated membranes. - Highlights: • Thin films are deposited on reverse osmosis membranes. • Amphiphilic thin films are resistant to protein attachment. • The permeation performance of the membranes is not affected by the coating. • The thin film coatings delayed the biofouling.

  3. Threshold concentration of easily assimilable organic carton in feedwater for biofouling of spiral-wound membranes.

    Science.gov (United States)

    Hijnen, W A M; Biraud, D; Cornelissen, E R; van der Kooij, D

    2009-07-01

    One of the major impediments in the application of spiral-wound membranes in water treatment or desalination is clogging of the feed channel by biofouling which is induced by nutrients in the feedwater. Organic carbon is, under most conditions, limiting the microbial growth. The objective of this study is to assess the relationship between the concentration of an easily assimilable organic compound such as acetate in the feedwater and the pressure drop increase in the feed channel. For this purpose the membrane fouling simulator (MFS) was used as a model for the feed channel of a spiral-wound membrane. This MFS unit was supplied with drinking water enriched with acetate at concentrations ranging from 1 to 1000 microg C x L(-1). The pressure drop (PD) in the feed channel increased at all tested concentrations but not with the blank. The PD increase could be described by a first order process based on theoretical considerations concerning biofilm formation rate and porosity decline. The relationship between the first order fouling rate constant R(f) and the acetate concentration is described with a saturation function corresponding with the growth kinetics of bacteria. Under the applied conditions the maximum R(f) (0.555 d(-1)) was reached at 25 microg acetate-C x L(-1) and the half saturation constant k(f) was estimated at 15 microg acetate-C x L(-1). This value is higher than k(s) values for suspended bacteria grown on acetate, which is attributed to substrate limited growth conditions in the biofilm. The threshold concentration for biofouling of the feed channel is about 1 microg acetate-C x L(-1).

  4. The influence of antiscalants on biofouling of RO membranes in seawater desalination.

    Science.gov (United States)

    Sweity, Amer; Oren, Yoram; Ronen, Zeev; Herzberg, Moshe

    2013-06-15

    Antiscalants are surface active polyelectrolyte compounds commonly used in reverse osmosis (RO) desalination processes to avoid membrane scaling. In spite of the significant roles of antiscalants in preventing membrane scaling, they are prone to enhance biofilm growth on RO membranes by either altering membrane surface properties or by serving as nutritional source for microorganisms. In this study, the contribution of antiscalants to membrane biofouling in seawater desalination was investigated. The effects of two commonly used antiscalants, polyphosphonate- and polyacrylate-based, were tested. The effects of RO membrane (DOW-Filmtec SW30 HRLE-400) exposure to antiscalants on its physico-chemical properties were studied, including the consequent effects on initial deposition and growth of the sessile microorganisms on the RO membrane surface. The effects of antiscalants on membrane physico-chemical properties were investigated by filtration of seawater supplemented with the antiscalants through flat-sheet RO membrane and changes in surface zeta potential and hydrophobicity were delineated. Adsorption of antiscalants to polyamide surfaces simulating RO membrane's polyamide layer and their effects on the consequent bacterial adhesion was tested using a quartz crystal microbalance with dissipation monitoring technology (QCM-D) and direct fluorescent microscopy. A significant increase in biofilm formation rate on RO membranes surface was observed in the presence of both types of antiscalants. Polyacrylate-based antiscalant was shown to enhance initial cell attachment as observed with the QCM-D and a parallel plate flow cell, due to rendering the polyamide surface more hydrophobic. Polyphosphonate-based antiscalants also increased biofilm formation rate, most likely by serving as an additional source of phosphorous to the seawater microbial population. A thicker biofilm layer was formed on the RO membrane when the polyacrylate-based antiscalant was used. Following

  5. The application of nitric oxide to control biofouling of membrane bioreactors.

    Science.gov (United States)

    Luo, Jinxue; Zhang, Jinsong; Barnes, Robert J; Tan, Xiaohui; McDougald, Diane; Fane, Anthony G; Zhuang, Guoqiang; Kjelleberg, Staffan; Cohen, Yehuda; Rice, Scott A

    2015-05-01

    A novel strategy to control membrane bioreactor (MBR) biofouling using the nitric oxide (NO) donor compound PROLI NONOate was examined. When the biofilm was pre-established on membranes at transmembrane pressure (TMP) of 88-90 kPa, backwashing of the membrane module with 80 μM PROLI NONOate for 45 min once daily for 37 days reduced the fouling resistance (Rf ) by 56%. Similarly, a daily, 1 h exposure of the membrane to 80 μM PROLI NONOate from the commencement of MBR operation for 85 days resulted in reduction of the TMP and Rf by 32.3% and 28.2%. The microbial community in the control MBR was observed to change from days 71 to 85, which correlates with the rapid TMP increase. Interestingly, NO-treated biofilms at 85 days had a higher similarity with the control biofilms at 71 days relative to the control biofilms at 85 days, indicating that the NO treatment delayed the development of biofilm bacterial community. Despite this difference, sequence analysis indicated that NO treatment did not result in a significant shift in the dominant fouling species. Confocal microscopy revealed that the biomass of biopolymers and microorganisms in biofilms were all reduced on the PROLI NONOate-treated membranes, where there were reductions of 37.7% for proteins and 66.7% for microbial cells, which correlates with the reduction in TMP. These results suggest that NO treatment could be a promising strategy to control biofouling in MBRs.

  6. Non-biofouling property of well-defined concentrated polymer brushes.

    Science.gov (United States)

    Yoshikawa, Chiaki; Qiu, Jun; Huang, Chih-Feng; Shimizu, Yoshihisa; Suzuki, Junji; van den Bosch, Edith

    2015-03-01

    The non-biofouling properties of polymer brushes of poly(2-hydroxyethyl methacrylate) (PHEMA), poly(2-hydroxyethyl acrylate) (PHEA), and poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) were comprehensively studied by varying graft densities (i.e., semi-dilute and concentrated regimes) and the thicknesses at the dry state of 2 and 10 nm. Semi-dilute polymer brushes (SDPBs) were prepared by grafting-to method and concentrated polymer brushes (CPBs) were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). The adsorptions of proteins with different sizes were investigated on the brushes by quartz crystal microbalance (QCM) from a view point of size-exclusion effect specific to the CPBs. We confirmed that due to the size exclusion effect, the CPBs of all the three much suppressed proteins adsorption and human umbilical vein endothelial cell (HUVEC) adhesion compared with the corresponding SDPBs. In order to investigate what type of proteins adsorbed on the brushes to trigger cell adhesion, we identified adsorbed proteins from fetal bovine serum on the brushes using a high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Proteins were only detected on the SDPBs. Interestingly, the number and type of identified proteins were different on the SDPBs, indicating that chemical composition of the SDPBs affects protein adsorption, hence the cell adhesion. The adsorption mechanism on the SDPBs could be due to the combination of protein-polymer interaction and physical inclusion, whereas CPBs exhibit size exclusion effect combined with neutral hydrophilic nature of polymer, thereby, that provides excellent non-biofouling property.

  7. The influence of antiscalants on biofouling of RO membranes in seawater desalination.

    Science.gov (United States)

    Sweity, Amer; Oren, Yoram; Ronen, Zeev; Herzberg, Moshe

    2013-06-15

    Antiscalants are surface active polyelectrolyte compounds commonly used in reverse osmosis (RO) desalination processes to avoid membrane scaling. In spite of the significant roles of antiscalants in preventing membrane scaling, they are prone to enhance biofilm growth on RO membranes by either altering membrane surface properties or by serving as nutritional source for microorganisms. In this study, the contribution of antiscalants to membrane biofouling in seawater desalination was investigated. The effects of two commonly used antiscalants, polyphosphonate- and polyacrylate-based, were tested. The effects of RO membrane (DOW-Filmtec SW30 HRLE-400) exposure to antiscalants on its physico-chemical properties were studied, including the consequent effects on initial deposition and growth of the sessile microorganisms on the RO membrane surface. The effects of antiscalants on membrane physico-chemical properties were investigated by filtration of seawater supplemented with the antiscalants through flat-sheet RO membrane and changes in surface zeta potential and hydrophobicity were delineated. Adsorption of antiscalants to polyamide surfaces simulating RO membrane's polyamide layer and their effects on the consequent bacterial adhesion was tested using a quartz crystal microbalance with dissipation monitoring technology (QCM-D) and direct fluorescent microscopy. A significant increase in biofilm formation rate on RO membranes surface was observed in the presence of both types of antiscalants. Polyacrylate-based antiscalant was shown to enhance initial cell attachment as observed with the QCM-D and a parallel plate flow cell, due to rendering the polyamide surface more hydrophobic. Polyphosphonate-based antiscalants also increased biofilm formation rate, most likely by serving as an additional source of phosphorous to the seawater microbial population. A thicker biofilm layer was formed on the RO membrane when the polyacrylate-based antiscalant was used. Following

  8. Anti-diffusion metal coated O-rings

    Energy Technology Data Exchange (ETDEWEB)

    Biallas, George Herman; Boyce, James Reid

    2016-03-22

    A method for inhibiting diffusion of gases and/or transmission of photons through elastomeric seals and a diffusion inhibiting elastomeric seal wherein at least a portion of the surface of a diffusion inhibiting elastomeric seal is coated with a compatibly-deformable, malleable metal coating.

  9. PLGA-PEG Nanoparticles Coated with Anti-CD45RO and Loaded with HDAC Plus Protease Inhibitors Activate Latent HIV and Inhibit Viral Spread

    Science.gov (United States)

    Tang, Xiaolong; Liang, Yong; Liu, Xinkuang; Zhou, Shuping; Liu, Liang; Zhang, Fujina; Xie, Chunmei; Cai, Shuyu; Wei, Jia; Zhu, Yongqiang; Hou, Wei

    2015-10-01

    Activating HIV-1 proviruses in latent reservoirs combined with inhibiting viral spread might be an effective anti-HIV therapeutic strategy. Active specific delivery of therapeutic drugs into cells harboring latent HIV, without the use of viral vectors, is a critical challenge to this objective. In this study, nanoparticles of poly(lactic-co-glycolic acid)-polyethylene glycol diblock copolymers conjugated with anti-CD45RO antibody and loaded with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) and/or protease inhibitor nelfinavir (Nel) were tested for activity against latent virus in vitro. Nanoparticles loaded with SAHA, Nel, and SAHA + Nel were characterized in terms of size, surface morphology, zeta potential, entrapment efficiency, drug release, and toxicity to ACH-2 cells. We show that SAHA- and SAHA + Nel-loaded nanoparticles can target latently infected CD4+ T-cells and stimulate virus production. Moreover, nanoparticles loaded with SAHA + NEL were capable of both activating latent virus and inhibiting viral spread. Taken together, these data demonstrate the potential of this novel reagent for targeting and eliminating latent HIV reservoirs.

  10. Bifunctional coating based on carboxymethyl chitosan with stable conjugated alkaline phosphatase for inhibiting bacterial adhesion and promoting osteogenic differentiation on titanium

    Science.gov (United States)

    Zheng, Dong; Neoh, Koon Gee; Kang, En-Tang

    2016-01-01

    In this work, alkaline phosphatase (ALP) was covalently immobilized on carboxymethyl chitosan (CMCS)-coated polydopamine (PDA)-functionalized Ti to achieve a bifunctional surface. Our results showed ∼89% reduction in Staphylococcus epidermidis adhesion on this surface compared to that on pristine Ti. The ALP-modified Ti supported cell proliferation, and significantly enhanced cellular ALP activity and calcium deposition of osteoblasts, human mesenchymal stem cells (hMSCs) and human adipose-derived stem cells (hADSCs). The extent of enhancement in the functions of these cells is dependent on the surface density of immobilized ALP. The substrate prepared using an ALP solution of 50 μg/cm2 resulted in 44%, 54% and 129% increase in calcium deposited by osteoblasts, hMSCs and hADSCs, respectively, compared to those cultured on pristine Ti. The ALP-modified substrates also promoted the osteogenic differentiation of hMSCs and hADSCs by up-regulating gene expressions of runt-related transcription factor 2 (RUNX2), osterix (OSX), and osteocalcin (OC) in the two types of stem cells. The surface-immobilized ALP was stable after being subjected to 1 h immersion in 70% ethanol and autoclaving at 121 °C for 20 min. However, the enzymatic bioactivity of the surface-immobilized ALP was reduced by about 50% after these substrates were immersed in phosphate buffered saline (PBS) or PBS containing lysozyme for 14 days.

  11. The photosystem II oxygen-evolving complex protein PsbP interacts with the coat protein of Alfalfa mosaic virus and inhibits virus replication.

    Science.gov (United States)

    Balasubramaniam, Muthukumar; Kim, Bong-Suk; Hutchens-Williams, Heather M; Loesch-Fries, L Sue

    2014-10-01

    Alfalfa mosaic virus (AMV) coat protein (CP) is essential for many steps in virus replication from early infection to encapsidation. However, the identity and functional relevance of cellular factors that interact with CP remain unknown. In an unbiased yeast two-hybrid screen for CP-interacting Arabidopsis proteins, we identified several novel protein interactions that could potentially modulate AMV replication. In this report, we focus on one of the novel CP-binding partners, the Arabidopsis PsbP protein, which is a nuclear-encoded component of the oxygen-evolving complex of photosystem II. We validated the protein interaction in vitro with pull-down assays, in planta with bimolecular fluorescence complementation assays, and during virus infection by co-immunoprecipitations. CP interacted with the chloroplast-targeted PsbP in the cytosol and mutations that prevented the dimerization of CP abolished this interaction. Importantly, PsbP overexpression markedly reduced virus accumulation in infected leaves. Taken together, our findings demonstrate that AMV CP dimers interact with the chloroplast protein PsbP, suggesting a potential sequestration strategy that may preempt the generation of any PsbP-mediated antiviral state. PMID:24940990

  12. Biofouling e biodeterioração química de argamassa de cimento portland em reservatório de usina hidroelétrica Biofouling and chemical biodeterioration in hydroeletric power plant portland cement mortar

    Directory of Open Access Journals (Sweden)

    Kleber Franke Portella

    2009-01-01

    Full Text Available Last decade Brazilian rivers experimented progressive biofouling of Limnoperna fortunei communities and Cordylophora caspia hydroids. The microhabitat is so favorable that in around 1.5 years L. fortunei increased from 0.39 to nearby 149,000 units/m². Ten Portland cement mortar samples were produced with 1: 3.5: 0.4 dosages and installed for 1 year at Salto Caxias Brazilian Power Plant reservoir in 0.5 m and 1.0 m deep to investigate the biofouling influence on hydraulic civil structures. SEM, EDS, visual investigation and XRF results indicate none direct chemical interrelationships between L. fortunei and the mortar samples. However C. caspia diminished the mortar surface resistance and caused cement paste leaching.

  13. Biofouling management by the BiosS-Treat {sup registered} -process for purification of surface water by reverse osmosis; Biofouling-Management mit dem BiosS-Treat {sup registered} -Verfahren fuer die Aufbereitung von Oberflaechenwaessern mittels Umkehrosmose-Anlagen

    Energy Technology Data Exchange (ETDEWEB)

    Keil, U.; Brueggendick, H. [STEAG encotec GmbH, Essen (Germany)

    2007-07-01

    In most plants biofouling problems are causing frequent membrane blocking with the consequences of degradation of plant performance and finally in many cases of unavoidable replacement of RO elements. In contrast to existing technologies the new biofouling management called BiosS-Treat {sup registered}, focuses on a preventive concept which is based on microbiological aspects. CEK engineering and STE-AG encotec have developed this new design of pre-treatment for the river water RO plant of the STEAG refinery power plant in Leuna, Germany. By BioS-Treat {sup registered} the availability of the RO plant was optimised significantly and the operating costs have been reduced to more then 60% in five years of operation. (orig.)

  14. Polymerization of cardanol using soybean peroxidase and its potential application as anti-biofilm coating material.

    Science.gov (United States)

    Kim, Yong Hwan; An, Eun Suk; Song, Bong Keun; Kim, Dong Shik; Chelikani, Rahul

    2003-09-01

    Soybean peroxidase (20 mg) catalyzed the oxidative polymerization of cardanol in 2-propanol/phospate buffer solution (25 ml, 1:1 v/v) and yielded 62% polycardanol over 6 h. Cobalt naphthenate (0.5% w/w) catalyzed the crosslinking of polycardanol and the final hardness of crosslinked polycardanol film exceeded 9 H scale as pencil scratch hardness, which shows a high potential as a commercial coating material. In addition, it showed an excellent anti-biofouling activity to Pseudomonas fluorescens compared to other polymeric materials such as polypropylene. PMID:14571976

  15. A novel approach to determine the efficacy of patterned surfaces for biofouling control in relation to its microfluidic environment.

    Science.gov (United States)

    Halder, Partha; Nasabi, Mahyar; Lopez, Francisco Javier Tovar; Jayasuriya, Niranjali; Bhattacharya, Satinath; Deighton, Margaret; Mitchell, Arnan; Bhuiyan, Muhammed Ali

    2013-01-01

    Biofouling, the unwanted growth of sessile microorganisms on submerged surfaces, presents a serious problem for underwater structures. While biofouling can be controlled to various degrees with different microstructure-based patterned surfaces, understanding of the underlying mechanism is still imprecise. Researchers have long speculated that microtopographies might influence near-surface microfluidic conditions, thus microhydrodynamically preventing the settlement of microorganisms. It is therefore very important to identify the microfluidic environment developed on patterned surfaces and its relation with the antifouling behaviour of those surfaces. This study considered the wall shear stress distribution pattern as a significant aspect of this microfluidic environment. In this study, patterned surfaces with microwell arrays were assessed experimentally with a real-time biofilm development monitoring system using a novel microchannel-based flow cell reactor. Finally, computational fluid dynamics simulations were carried out to show how the microfluidic conditions were affecting the initial settlement of microorganisms.

  16. Biofouling Growth in Cold Estuarine Waters and Evaluation of Some Chitosan and Copper Anti-Fouling Paints

    OpenAIRE

    Karine Lemarchand; Claudie Bonnet; Émilien Pelletier

    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 ...

  17. Biofouling resistance of boron-doped diamond neural stimulation electrodes is superior to titanium nitride electrodes in vivo

    DEFF Research Database (Denmark)

    Meijs, Suzan; Alcaide, Maria; Sørensen, Charlotte;

    2016-01-01

    OBJECTIVE: The goal of this study was to assess the electrochemical properties of boron-doped diamond (BDD) electrodes in relation to conventional titanium nitride (TiN) electrodes through in vitro and in vivo measurements. APPROACH: Electrochemical impedance spectroscopy, cyclic voltammetry and ...... electrodes possess a superior biofouling resistance, which provides significantly stable electrochemical properties both in protein solution as well as in vivo compared to TiN electrodes....

  18. Antifouling coatings influence both abundance and community structure of colonizing biofilms: a case study in the Northwestern Mediterranean Sea.

    Science.gov (United States)

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

    2014-08-01

    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. Morbus Coats

    Science.gov (United States)

    Förl, B.; Schmack, I.; Grossniklaus, H.E.; Rohrschneider, K.

    2010-01-01

    Der fortgeschrittene Morbus Coats stellt im Kleinkindalter eine der schwierigsten Differenzialdiagnosen zum Retinoblastom dar. Wir beschreiben die klinischen und histologischen Befunde zweier Jungen im Alter von 9 und 21 Monaten mit einseitiger Leukokorie. Trotz umfassender Diagnostik mittels Narkoseuntersuchung, MRT und Ultraschall konnte ein Retinoblastom nicht sicher ausgeschlossen werden, und es erfolgte eine Enukleation. Histologisch wurde die Diagnose eines Morbus Coats gesichert. Da eine differenzialdiagnostische Abgrenzung zwischen Morbus Coats und Retinoblastom schwierig sein kann, halten wir in zweifelhaften Fällen auch angesichts der eingeschränkten Visusprognose und potenzieller Sekundärkomplikationen beim fortgeschrittenen Morbus Coats eine Enukleation für indiziert. PMID:18299842

  20. Pilot-scale cooling tower to evaluate corrosion, scaling, and biofouling control strategies for cooling system makeup water.

    Science.gov (United States)

    Chien, S H; Hsieh, M K; Li, H; Monnell, J; Dzombak, D; Vidic, R

    2012-02-01

    Pilot-scale cooling towers can be used to evaluate corrosion, scaling, and biofouling control strategies when using particular cooling system makeup water and particular operating conditions. To study the potential for using a number of different impaired waters as makeup water, a pilot-scale system capable of generating 27,000 kJ∕h heat load and maintaining recirculating water flow with a Reynolds number of 1.92 × 10(4) was designed to study these critical processes under conditions that are similar to full-scale systems. The pilot-scale cooling tower was equipped with an automatic makeup water control system, automatic blowdown control system, semi-automatic biocide feeding system, and corrosion, scaling, and biofouling monitoring systems. Observed operational data revealed that the major operating parameters, including temperature change (6.6 °C), cycles of concentration (N = 4.6), water flow velocity (0.66 m∕s), and air mass velocity (3660 kg∕h m(2)), were controlled quite well for an extended period of time (up to 2 months). Overall, the performance of the pilot-scale cooling towers using treated municipal wastewater was shown to be suitable to study critical processes (corrosion, scaling, biofouling) and evaluate cooling water management strategies for makeup waters of complex quality.

  1. Biofouling of reverse osmosis membranes used in river water purification for drinking purposes: analysis of microbial populations.

    Science.gov (United States)

    Chiellini, Carolina; Iannelli, Renato; Modeo, Letizia; Bianchi, Veronica; Petroni, Giulio

    2012-01-01

    Biofouling in water treatment processes represents one of the most frequent causes of plant performance decline. Investigation of clogged membranes (reverse osmosis membranes, microfiltration membranes and ultrafiltration membranes) is generally performed on fresh membranes. In the present study, a multidisciplinary autopsy of a reverse osmosis membrane (ROM) was conducted. The membrane, which was used in sulfate-rich river water purification for drinking purposes, had become inoperative after 6 months because of biofouling and was later stored for 18 months in dry conditions before analysis. SSU rRNA gene library construction, clone sequencing, T-RFLP, light microscope, and scanning electron microscope (SEM) observations were used to identify the microorganisms present on the membrane and possibly responsible for biofouling at the time of removal. The microorganisms were mainly represented by bacteria belonging to the phylum Actinobacteria and by a single protozoan species belonging to the Lobosea group. The microbiological analysis was interpreted in the context of the treatment plant operations to hypothesize as to the possible mechanisms used by microorganisms to enter the plant and colonize the ROM surface.

  2. Effect of microbial community structure on organic removal and biofouling in membrane adsorption bioreactor used in seawater pretreatment

    KAUST Repository

    Jeong, Sanghyun

    2016-03-03

    Membrane bioreactors (MBRs) were operated on-site for 56 d with different powdered activated carbon (PAC) dosages of 0, 1.5 and 5.0 g/L to pretreat seawater for reverse osmosis desalination. It was hypothesized that PAC would stimulate adsorption and biological degradation of organic compounds. The microbial communities responsible for biofouling on microfiltration (MF) membranes and biological organic removal in MBR were assessed using terminal restriction fragment length polymorphism fingerprinting and 454-pyrosequencing. The PAC addition improved assimilable organic carbon removal (53-59%), and resulted in reduced biofouling development on MF (> 50%) with only a marginal development in trans-membrane pressure. Interestingly, the bacterial community composition was significantly differentiated by the PAC addition. Cyanobacterium, Pelagibaca and Maricoccus were dominant in the PAC-free conditions, while Thiothrix and Sphingomonas were presumably responsible for the better reactor performances in PAC-added conditions. In contrast, the archaeal communities were consistent with predominance of Candidatus Nitrosopumilus. These data therefore show that the addition of PAC can improve MBR performance by developing different bacterial species, controlling AOC and associated biofouling on the membranes.

  3. 不同营养下混合菌种微生物污垢生长机理与交互作用%Growth and interaction mechanism of multi-strain biofouling under different nutrient levels

    Institute of Scientific and Technical Information of China (English)

    杨倩鹏; 陈晓东; 田磊; 史琳

    2013-01-01

    再生水源热泵能有效回用废热,但再生水换热器的微生物污垢问题一直没有完全解决,严重影响换热效率和系统安全.利用长期监测并且进行16S rRNA鉴定得到的再生水及其污垢中两种主要代表菌属芽孢杆菌属和气单胞菌属,在实验室内配制模拟流体进行混合菌种微生物污垢实验.通过在特制的机理流道上进行不同菌种比例和不同营养物质浓度的污垢生长实验,得出芽孢杆菌属和气单胞菌属的单独生长规律和混合生长规律,总结了混合生长时两种菌属的协同和抑制规律,同时考察了营养物质浓度对生长规律和交互作用的影响.结果表明:芽孢杆菌属成垢能力较强,细胞分裂速度高,耐贫营养能力强;气单胞菌属成垢能力弱于芽孢杆菌属,但分泌物生成速率高,可以与芽孢杆菌属协同生长;两种菌属交互作用在不同阶段和条件下,协同与抑制作用共存并轮流占据主导.%Heat pump system is an effective method for heat recovery of a treated sewage source, but biofouling on heat exchanger is still a problem to be solved, and may affect seriously efficiency and security of the system. By long term monitoring and 16S rRNA identification, two major bacteria genus, Bacillus sp. and Aeromonas sp. , were selected for multi-strain biofouling experiment of a model fluid in laboratory. By the experiment of foul growth performed on a purpose made channel at various bacteria ratios and nutrient levels, the regular patterns of single and mixed microbe growth of Bacillus sp. and Aeromonas sp. were revealed, their synergy and inhibition interaction summarized, and the effect of nutrient levels on their growth mechanism and interaction also investigated. The results indicated that the Bacillus sp. has strong ability in biofouling, in high multiple rates, and high tolerance to poor nutrient level. The biofouling of Aeromonas sp. is weak relatively, but high secretion rate that may

  4. Studies with anti fouling coating on seawater intake system screens of MAPS

    International Nuclear Information System (INIS)

    Biofouling has been a concern for cooling water systems of coastal power plants and the same is being experienced in Madras Atomic Power Station (MAPS). Macro fouling organisms cause major problems for smooth operation and maintenance of the cooling water system. The cooling water intake structures particularly the screens, which act as the barrier for marine organisms to enter into the cooling water system, gets fouled severely in a short period of time. Though chlorination is being done to control biofouling, it is ineffective due to the inward flow of seawater. Severely fouled gates necessitate frequent cleaning and maintenance which involves lifting of heavy structures, laborious manual cleaning and maintenance. In order to find remedial measures for the said concern, studies have been taken up for identification of simple but effective methods in controlling bio fouling. Accordingly studies with Anti Fouling Coating (AFC) applications have been identified and field studies were carried out to review its effectiveness in meeting the given requirement. One of the gates was coated with Anti Fouling Coating (AFC) and exposed to sea water and the bio fouling tendency was regularly monitored. It was noted that the AFC coated gate was observed to have less bio fouling compared to the in-practice coal tar epoxy coatings. The small quantity of fouling deposits was generally observed to be on the side opposite to the sea water current. The area exposed to sea water currents had relatively less biogrowth. The dislodgement or removal of bio growth could be achieved by gentle pressure or scrapping thus demonstrating its effectiveness in controlling the bio fouling. Studies are also in progress to with Foul release coatings (FRC) to study its effectiveness. (author)

  5. Biofouling community pattern on various metallic surfaces in the coastal waters of Kalpakkam, Southwestern Bay of Bengal

    International Nuclear Information System (INIS)

    Biofouling causes great operational hazard in different marine installations across the globe. And the expenditure incurred on combating biofouling is astounding. It is reported that shut down of a 235 MW (e) power station due to fouling, costs about 170 lakhs (at Rs. 3.00 per kw/h) per day. Because of this economic implication, biofouling has been a thrust area of study for the marine researchers. To assess the biofouling pattern, metallic surfaces are the best options because of their extensive use at various installations in the marine environment. Hence, knowledge on qualitative and quantitative aspects of biofouling with respect to metal surfaces is of great value to design an efficient fouling control strategy. Keeping this in mind, nine types of metal (SS-316, SS-304, MS, Titanium, Admiralty Brass, Aluminum Brass, Copper, Monel and Cupro-nickel) panels (12 x 9 x 0.1 cm) were exposed to coastal water of Kalpakkam from MAPS jetty at a depth of 2 m below the lowest low tide. Results indicated that copper based panels were found to be foul-free except monel. Although, fouling settlement was encountered on monel, the adherence was weak. Non-copper based metals showed 100% area coverage with high population density. However, in case of MS, due to exfoliation of corrosion deposits, unevenness in fouling colonization at later stages of development took place, though the early settlement was unaffected by initial corrosion. As expected, Titanium showed high rate of fouling growth along with high fouling diversity compared to other non-copper based metals. Absence of specific foulants such as, crustaceans and algae on Titanium surface reported by others was not observed during our study. The information on Titanium would be handy for Prototype Fast Breeder Reactor (PFBR) cooling water system wherein, the same has been selected as condenser and process water heat exchanger material. For non-copper based alloys including monel the fouling load ranged from 18 to 40 g

  6. Inhibition of the radiolytic hydrogen production in the nuclear waste of 'bitumen coated' type: study of the interaction between hydrogen and cobalt hydroxo-sulphide

    International Nuclear Information System (INIS)

    In the nuclear field in France, the bitumen is mainly used for the conditioning of the radioactive muds generated by the fuel reprocessing. However, the self-irradiation of the bitumen induces a production of hydrogen which generates safety problems. The comparison of various storage sites showed that the presence of cobalt hydroxo sulphide limited such a production. Consequently, this compound was regarded as an 'inhibitor of radiolytic hydrogen production'. However, the origin of this phenomenon was not clearly identified. In order to propose an explanation to this inhibition phenomenon, model organic molecules were used to represent the components of the bitumen. Irradiations were carried out by protons to simulate the alpha radiolysis. The organic molecules irradiations by a proton beam showed that cobalt hydroxo sulphide CoSOH, does not act as a hydrogenation catalyst of unsaturated hydrocarbons, nor as a radicals scavenger, but consists of a trap of hydrogen. Experiments of hydrogen trapping at ambient temperature were carried out according to two techniques: gravimetry and manometry. The solid was characterized before and after interaction with hydrogen (infrared and Raman spectroscopies, X-ray diffraction). The initial solid was composed of amorphous cobalt hydroxo sulphide and a minor phase of cobalt hydroxide. The gravimetry and manometry experiments showed that the maximum of hydrogen trapping capacity is equal to 0.59 ± 0.18 mole of hydrogen per mole of cobalt. After interaction with hydrogen, the Co(OH)2 phase disappeared and a new solid phase appeared corresponding to Co9S8. These observations, as well as the analysis of the gas phase, made it possible to conclude with the following reaction (1): 9 CoSOH + 11/2 H2 = Co9S8 + 9 H2O + H2S (1). Gravimetry experiments at temperatures between 50 and 210 C revealed the desorption of water but not of hydrogen sulphide. The absence of hydrogen sulphide in gaseous phase and the Co(OH)2 phase disappearance

  7. A Multifunctional Coating for Autonomous Corrosion Control

    Science.gov (United States)

    Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott t.

    2011-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of existing microcapsulation designs, the corrosion controlled release function that triggers the delivery of corrosion indicators and inhibitors on demand, only when and where needed. Microencapsulation of self-healing agents for autonomous repair of mechanical damage to the coating is also being pursued. Corrosion indicators, corrosion inhibitors, as well as self-healing agents, have been encapsulated and dispersed into several paint systems to test the corrosion detection, inhibition, and self-healing properties of the coating. Key words: Corrosion, coating, autonomous corrosion control, corrosion indication, corrosion inhibition, self-healing coating, smart coating, multifunctional coating, microencapsulation.

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

    Science.gov (United States)

    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. PMID:24594048

  9. Prevention and protection of the effects of biocorrosion and biofouling minimizing the environmental impact

    Directory of Open Access Journals (Sweden)

    Gómez de Saravia, S. G.

    2003-12-01

    Full Text Available Biocorrosion and biofouling processes are mediated by microorganisms adhered to the metal surfaces or embedded in a gelatinous matrix called biofilm. Biofilms affect the interaction between metals and the environment not only in deleterious processes like corrosion but also in several biological processes applied to materials recovery and handling. The growth of the microorganisms capable to induce biocorrosion is conditioned by favorable environmental conditions. However, the chemical agents generally used to prevent or protect metallic structures from biocorrosion are highly toxic and after use can have a negative impact on the environment. Four different approaches developed in our laboratory to prevent and control biocorrosion but minimizing the environmental impact, are successively presented in this paper: a the use of ozone as an environmentally friend biocide for cooling water systems; b the assay of the effectiveness of natural biocides on planktonic and sessile bacteria; c the potential use of film forming corrosion inhibitors; d the use of innovative preventing substances.

    Los procesos de biocorrosión y biofouling están mediados por microorganismos que adhieren a las superficies metálicas embebidos en una matriz gelatinosa llamada biofilm. Los biofilms afectan a la interacción entre metales y el medio ambiente, no solo a través de procesos deletéreos tales como la corrosión sino, también, en el manipuleo de diversos materiales. El crecimiento de los microorganismos capaces de inducir biocorrosión esta condicionado por un medio ambiente favorable. Sin embargo, generalmente, los agentes químicos usados para prevenir o proteger las estructuras metálicas de la biocorrosión son altamente tóxicos y su uso puede tener un impacto negativo para el ambiente. En este trabajo se presentan cuatro vías diferentes, desarrolladas en nuestro laboratorio, para prevenir y controlar la biocorrosión minimizando el impacto

  10. Advanced Monitoring and Characterization of Biofouling in Gravity-driven Membrane Filtration

    KAUST Repository

    Wang, Yiran

    2016-05-01

    Gravity-driven membrane (GDM) filtration is one of the promising membrane bioreactor (MBR) technologies. It operates at a low pressure by gravity, requiring a minimal energy. Thus, it exhibits a great potential for a decentralized system, conducting household in developing and transition countries. Biofouling is a universal problem in almost all membrane filtration applications, leading to the decrease in flux or the increase in transmembrane pressure depending on different operation mode. Air scoring or regular membrane cleaning has been utilized for fouling mitigation, which requires increased energy consumption as well as complicated operations. Besides, repeating cleaning will trigger the deterioration of membranes and shorten their lifetime, elevating cost expenditures accordingly. In this way, GDM filtration stands out from conventional MBR technologies in a long-term operation with relative stable flux, which has been observed in many studies. The objective of this study was to monitor the biofilm development on a flat sheet membrane submerged in a GDM reactor with constant gravitational pressure. Morphology of biofilm layer in a fixed position was acquired by an in-situ and on-line OCT (optical coherence tomography) scanning at regular intervals for both visual investigation and structure analysis. The calculated thickness and roughness were compared to the variation of flux, fouling resistance and permeate quality, showing expected consistency. At the end of experiment, the morphology of entire membrane surface was scanned and recorded by OCT. Membrane autopsy was carried out for biofilm composition analysis by total organic carbon (TOC) and liquid chromatography with organic carbon detection (LC-OCD). In addition, biomass concentration was obtained by flow cytometer and adenosine tri-phosphate (ATP) method. The data of biofilm components indicated a homogeneous biofilm structure formed after a long-term running of the GDM system, based on the morphology

  11. Controlled Architecture of Dual-Functional Block Copolymer Brushes on Thin-Film Composite Membranes for Integrated "Defending" and "Attacking" Strategies against Biofouling.

    Science.gov (United States)

    Ye, Gang; Lee, Jongho; Perreault, François; Elimelech, Menachem

    2015-10-21

    We report a new macromolecular architecture of dual functional block copolymer brushes on commercial thin-film composite (TFC) membranes for integrated "defending" and "attacking" strategies against biofouling. Mussel-inspired catechol chemistry is used for a convenient immobilization of initiator molecules to the membrane surface with the aid of polydopamine (PDA). Zwitterionic polymer brushes with strong hydration capacity and quaternary ammonium salt (QAS) polymer brushes with bactericidal ability are sequentially grafted on TFC membranes via activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP), an environmentally benign and controlled polymerization method. Measurement of membrane intrinsic transport properties in reverse osmosis experiments shows that the modified TFC membrane maintains the same water permeability and salt selectivity as the pristine TFC membrane. Chemical force microscopy and protein/bacterial adhesion studies are carried out for a comprehensive evaluation of the biofouling resistance and antimicrobial ability, demonstrating low biofouling propensity and excellent bacterial inactivation for the modified TFC membrane. We conclude that this polymer architecture, with complementary "defending" and "attacking" capabilities, can effectively prevent the attachment of biofoulants and formation of biofilms and thereby significantly mitigate biofouling on TFC membranes.

  12. Effect of calcium ions on the evolution of biofouling by Bacillus subtilis in plate heat exchangers simulating the heat pump system used with treated sewage in the 2008 Olympic Village.

    Science.gov (United States)

    Tian, Lei; Chen, Xiao Dong; Yang, Qian Peng; Chen, Jin Chun; Shi, Lin; Li, Qiong

    2012-06-01

    Heat pump systems using treated sewage water as the heat source were used in the Beijing Olympic Village for domestic heating and cooling. However, considerable biofouling occurred in the plate heat exchangers used in the heat pump system, greatly limiting the system efficiency. This study investigates the biofouling characteristics using a plate heat exchanger in parallel with a flow cell system to focus on the effect of calcium ions on the biofilm development. The interactions between the microorganisms and Ca(2+) enhances both the extent and the rate of biofilm development with increasing Ca(2+) concentration, leading to increased heat transfer and flow resistances. Three stages of biofouling development were identified in the presence of Ca(2+) from different biofouling mass growth rates with an initial stage, a rapid growth stage and an extended growth stage. Each growth stage had different biofouling morphologies influenced by the Ca(2+) concentration. The effects of Ca(2+) on the biofouling heat transfer and flow resistances had a synergistic effect related to both the biofouling mass and the morphology. The effect of Ca(2+) on the biofouling development was most prominent during the rapid growth stage. PMID:22391321

  13. Effect of calcium ions on the evolution of biofouling by Bacillus subtilis in plate heat exchangers simulating the heat pump system used with treated sewage in the 2008 Olympic Village.

    Science.gov (United States)

    Tian, Lei; Chen, Xiao Dong; Yang, Qian Peng; Chen, Jin Chun; Shi, Lin; Li, Qiong

    2012-06-01

    Heat pump systems using treated sewage water as the heat source were used in the Beijing Olympic Village for domestic heating and cooling. However, considerable biofouling occurred in the plate heat exchangers used in the heat pump system, greatly limiting the system efficiency. This study investigates the biofouling characteristics using a plate heat exchanger in parallel with a flow cell system to focus on the effect of calcium ions on the biofilm development. The interactions between the microorganisms and Ca(2+) enhances both the extent and the rate of biofilm development with increasing Ca(2+) concentration, leading to increased heat transfer and flow resistances. Three stages of biofouling development were identified in the presence of Ca(2+) from different biofouling mass growth rates with an initial stage, a rapid growth stage and an extended growth stage. Each growth stage had different biofouling morphologies influenced by the Ca(2+) concentration. The effects of Ca(2+) on the biofouling heat transfer and flow resistances had a synergistic effect related to both the biofouling mass and the morphology. The effect of Ca(2+) on the biofouling development was most prominent during the rapid growth stage.

  14. Potential biofouling of spacecraft propellant systems due to contaminated deionized water

    Science.gov (United States)

    Hogue, Patrick

    2006-08-01

    Deionized (DI) water, with a density close to hydrazine, is used to fill spacecraft propellant tanks for mechanical testing during ground operations, after which is it removed and the tanks dried for use with anhydrous hydrazine. Pure nitrogen is used as a pressurant during storage and during water fill and drain operations. Since DI water systems are notorious for contamination by slime-forming bacteria, DI water intended for use in New Horizons and STEREO hydrazine tanks at APL was assessed for microorganism content using the heterotrophic plate count (HPC) method. Results show that some growth occurred during storage of DI water in propellant tanks, however not at the logarithmic rate associated with well-nourished bacteria. Ralstonia and Burkholderia were present in DI water on-loaded however only Ralstonia was present in off-loaded water. One possible source of nutrients during water storage in propellant tanks is organic material originating from the EPDM (EPR per AF-E-332) expulsion diaphragm. This paper will demonstrate potential for bio-fouling of spacecraft propulsion systems due to growth of slime-forming bacteria and will suggest that specifications controlling microorganism content should be imposed on water used for spacecraft ground testing.

  15. Composition and variability of biofouling organisms in seawater reverse osmosis desalination plants.

    Science.gov (United States)

    Zhang, Minglu; Jiang, Sunny; Tanuwidjaja, Dian; Voutchkov, Nikolay; Hoek, Eric M V; Cai, Baoli

    2011-07-01

    Seawater reverse osmosis (SWRO) membrane biofouling remains a common challenge in the desalination industry, but the marine bacterial community that causes membrane fouling is poorly understood. Microbial communities at different stages of treatment processes (intake, cartridge filtration, and SWRO) of a desalination pilot plant were examined by both culture-based and culture-independent approaches. Bacterial isolates were identified to match the genera Shewanella, Alteromonas, Vibrio, and Cellulophaga based on 16S rRNA gene sequencing analysis. The 16S rRNA gene clone library of the SWRO membrane biofilm showed that a filamentous bacterium, Leucothrix mucor, which belongs to the gammaproteobacteria, accounted for nearly 30% of the clone library, while the rest of the microorganisms (61.2% of the total clones) were related to the alphaproteobacteria. 16S rRNA gene terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that bacteria colonizing the SWRO membrane represented a subportion of microbes in the source seawater; however, they were quite different from those colonizing the cartridge filter. The examination of five SWRO membranes from desalination plants located in different parts of the world showed that although the bacterial communities from the membranes were not identical to each other, some dominant bacteria were commonly observed. In contrast, bacterial communities in source seawater were significantly different based on location and season. Microbial profiles from 14 cartridge filters collected from different plants also revealed spatial trends. PMID:21551282

  16. A superhydrophilic nitinol shape memory alloy with enhanced anti-biofouling and anti-corrosion properties.

    Science.gov (United States)

    Song, K; Min, T; Jung, J-Y; Shin, D; Nam, Y

    2016-01-01

    This work reports on a nitinol (NiTi) surface modification scheme based on a chemical oxidation method, and characterizes its effects on wetting, biofouling and corrosion. The scheme developed is also compared with selected previous oxidation methods. The proposed method turns NiTi into superhydrophilic in ~5 min, and the static contact angle and contact angle hysteresis were measured to be ~7° and ~12°, respectively. In the PRP (platelet rich plasma) test, platelet adhesion was reduced by ~89% and ~77% respectively, compared with the original NiTi and the NiTi treated with the previous chemical oxidation scheme. The method developed provides a high (~1.1 V) breakdown voltage, which surpasses the ASTM standard for intervascular medical devices. It also provides higher superhydrophilicity, hemo-compatibility and anti-corrosion resistance than previous oxidation schemes, with a significantly reduced process time (~5 min), and will help the development of high performance NiTi devices.

  17. Nanoclay embedded mixed matrix PVDF nanocomposite membrane: Preparation, characterization and biofouling resistance

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, Hamid [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Department of Civil Engineering, Razi University, 67149 Kermanshah (Iran, Islamic Republic of); Ghaemi, Negin, E-mail: negin_ghaemi@kut.ac.ir [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Madaeni, Sayed S. [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Daraei, Parisa [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Khadivi, Mohammad Ali [Friedrich-Alexander University, Erlangen-Nuremberg, Egerland Strasse 3, D-91058 Erlangen (Germany); Falsafi, Monir [Department of Chemistry, Faculty of Science, Razi University, 67149 Kermanshah (Iran, Islamic Republic of)

    2014-09-15

    Highlights: • Nanocomposite membranes were prepared by addition of OMMT to PVDF membrane. • Addition of nanoclay considerably increased the hydrophilicity of PVDF membrane. • Nanocomposite membranes had higher water flux and antifouling properties. • Fouling of membranes blended with nanoclay (<4 wt.%) reduced. - Abstract: In this paper, nanocomposite PVDF/nanoclay membranes were prepared with addition of different concentrations of organically modified montmorillonite (OMMT) into the polymeric casting solution using combination of solution dispersion and phase inversion methods. Membranes were characterized by use of X-ray diffraction (XRD), water contact angle, scanning electron microscopy (SEM) and atomic force microscopy (AFM), and their performances were evaluated in terms of pure water flux and fouling parameters. The surface hydrophilicity of all nanocomposites markedly improved compared to nascent PVDF. In addition, XRD patterns revealed the formation of intercalated layers of mineral clays in PVDF matrix. SEM and AFM images showed that addition of OMMT resulted in nanocomposite membranes with thinner skin layer and higher porosity rather than PVDF membranes. Pure water flux of PVDF/OMMT membranes increased significantly (particularly for fabricated membranes by 4 and 6 wt.% OMMT) compared to that of PVDF membrane. Moreover, nanocomposite membranes showed the elevated antifouling properties, and flux recovery of nascent PVDF membranes increased from 51 to 72% with addition of 2 wt.% OMMT nanoparticles. These nanocomposite membranes also offered a remarkable reusability and durability against biofouling.

  18. Biofouling on buoyant marine plastics: An experimental study into the effect of size on surface longevity.

    Science.gov (United States)

    Fazey, Francesca M C; Ryan, Peter G

    2016-03-01

    Recent estimates suggest that roughly 100 times more plastic litter enters the sea than is found floating at the sea surface, despite the buoyancy and durability of many plastic polymers. Biofouling by marine biota is one possible mechanism responsible for this discrepancy. Microplastics (plastic items with high surface area to volume ratios sank more rapidly by submerging 15 different sizes of polyethylene samples in False Bay, South Africa, for 12 weeks to determine the time required for samples to sink. All samples became sufficiently fouled to sink within the study period, but small samples lost buoyancy much faster than larger ones. There was a direct relationship between sample volume (buoyancy) and the time to attain a 50% probability of sinking, which ranged from 17 to 66 days of exposure. Our results provide the first estimates of the longevity of different sizes of plastic debris at the ocean surface. Further research is required to determine how fouling rates differ on free floating debris in different regions and in different types of marine environments. Such estimates could be used to improve model predictions of the distribution and abundance of floating plastic debris globally. PMID:26803792

  19. Composition and variability of biofouling organisms in seawater reverse osmosis desalination plants.

    Science.gov (United States)

    Zhang, Minglu; Jiang, Sunny; Tanuwidjaja, Dian; Voutchkov, Nikolay; Hoek, Eric M V; Cai, Baoli

    2011-07-01

    Seawater reverse osmosis (SWRO) membrane biofouling remains a common challenge in the desalination industry, but the marine bacterial community that causes membrane fouling is poorly understood. Microbial communities at different stages of treatment processes (intake, cartridge filtration, and SWRO) of a desalination pilot plant were examined by both culture-based and culture-independent approaches. Bacterial isolates were identified to match the genera Shewanella, Alteromonas, Vibrio, and Cellulophaga based on 16S rRNA gene sequencing analysis. The 16S rRNA gene clone library of the SWRO membrane biofilm showed that a filamentous bacterium, Leucothrix mucor, which belongs to the gammaproteobacteria, accounted for nearly 30% of the clone library, while the rest of the microorganisms (61.2% of the total clones) were related to the alphaproteobacteria. 16S rRNA gene terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that bacteria colonizing the SWRO membrane represented a subportion of microbes in the source seawater; however, they were quite different from those colonizing the cartridge filter. The examination of five SWRO membranes from desalination plants located in different parts of the world showed that although the bacterial communities from the membranes were not identical to each other, some dominant bacteria were commonly observed. In contrast, bacterial communities in source seawater were significantly different based on location and season. Microbial profiles from 14 cartridge filters collected from different plants also revealed spatial trends.

  20. Composition and Variability of Biofouling Organisms in Seawater Reverse Osmosis Desalination Plants ▿ †

    Science.gov (United States)

    Zhang, Minglu; Jiang, Sunny; Tanuwidjaja, Dian; Voutchkov, Nikolay; Hoek, Eric M. V.; Cai, Baoli

    2011-01-01

    Seawater reverse osmosis (SWRO) membrane biofouling remains a common challenge in the desalination industry, but the marine bacterial community that causes membrane fouling is poorly understood. Microbial communities at different stages of treatment processes (intake, cartridge filtration, and SWRO) of a desalination pilot plant were examined by both culture-based and culture-independent approaches. Bacterial isolates were identified to match the genera Shewanella, Alteromonas, Vibrio, and Cellulophaga based on 16S rRNA gene sequencing analysis. The 16S rRNA gene clone library of the SWRO membrane biofilm showed that a filamentous bacterium, Leucothrix mucor, which belongs to the gammaproteobacteria, accounted for nearly 30% of the clone library, while the rest of the microorganisms (61.2% of the total clones) were related to the alphaproteobacteria. 16S rRNA gene terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that bacteria colonizing the SWRO membrane represented a subportion of microbes in the source seawater; however, they were quite different from those colonizing the cartridge filter. The examination of five SWRO membranes from desalination plants located in different parts of the world showed that although the bacterial communities from the membranes were not identical to each other, some dominant bacteria were commonly observed. In contrast, bacterial communities in source seawater were significantly different based on location and season. Microbial profiles from 14 cartridge filters collected from different plants also revealed spatial trends. PMID:21551282

  1. Effect of flow velocity, substrate concentration and hydraulic cleaning on biofouling of reverse osmosis feed channels

    KAUST Repository

    Radu, Andrea I.

    2012-04-01

    A two-dimensional mathematical model coupling fluid dynamics, salt and substrate transport and biofilm development in time was used to investigate the effects of cross-flow velocity and substrate availability on biofouling in reverse osmosis (RO)/nanofiltration (NF) feed channels. Simulations performed in channels with or without spacer filaments describe how higher liquid velocities lead to less overall biomass amount in the channel by increasing the shear stress. In all studied cases at constant feed flow rate, biomass accumulation in the channel reached a steady state. Replicate simulation runs prove that the stochastic biomass attachment model does not affect the stationary biomass level achieved and has only a slight influence on the dynamics of biomass accumulation. Biofilm removal strategies based on velocity variations are evaluated. Numerical results indicate that sudden velocity increase could lead to biomass sloughing, followed however by biomass re-growth when returning to initial operating conditions. Simulations show particularities of substrate availability in membrane devices used for water treatment, e.g., the accumulation of rejected substrates at the membrane surface due to concentration polarization. Interestingly, with an increased biofilm thickness, the overall substrate consumption rate dominates over accumulation due to substrate concentration polarization, eventually leading to decreased substrate concentrations in the biofilm compared to bulk liquid. © 2012 Elsevier B.V.

  2. Sprayed coatings

    Science.gov (United States)

    Steffens, H. D.

    1980-03-01

    Thermal spraying is shown to be an efficient means for the protection of surface areas against elevated temperature, wear, corrosion, hot gas corrosion, and erosion in structural aircraft components. Particularly in jet engines, numerous parts are coated by flame, detonation, or plasma spraying techniques. The applied methods of flame, detonation, and plasma spraying are explained, as well as electric arc spraying. Possibilities for spray coatings which meet aircraft service requirements are discussed, as well as methods for quality control, especially nondestructive test methods. In particular, coating characteristics and properties obtained by different spray methods are described, and special attention is paid to low pressure plasma spraying.

  3. Hard coatings

    OpenAIRE

    Dan, J.; Boving, H.; Hintermann, H.

    1993-01-01

    Hard, wear resistant and low friction coatings are presently produced on a world-wide basis, by different processes such as electrochemical or electroless methods, spray technologies, thermochemical, CVD and PVD. Some of the most advanced processes, especially those dedicated to thin film depositions, basically belong to CVD or PVD technologies, and will be looked at in more detail. The hard coatings mainly consist of oxides, nitrides, carbides, borides or carbon. Over the years, many process...

  4. Antifouling effect of two saturated copper coatings applied on carbon steel structures

    Directory of Open Access Journals (Sweden)

    Guiamet, P. S.

    2008-10-01

    Full Text Available Biofouling is the colonization of man-made substrata by sessile organisms. The aim of this paper is to evaluate the performance of two antifouling saturated copper coating. Bioassays were carried out at a harbor in Argentine (38°02’S- 57°32’W. During six months, one series of pipes and panels were removed monthly to estimate the recruitment of macro and microfouling species and immediately replaced by clean ones. Another series was removed from the beginning of exposure to monitor the development of the established community (accumulative pipes and panels along six months. Data obtained from control (without a saturated copper coating and saturated-copper coated pipes and panels were compared in order to estimate performance of the coating. One of two saturated copper coating demonstrated a good effect antifouling.

    El biofouling es la colonización por organismos sésiles en sistemas de sustratos hechos por el hombre. El objetivo fue evaluar el efecto antifouling de dos cubiertas saturadas de cobre. Los estudios se llevaron a cabo en un puerto de la Argentina (38°02’S-57°32’W. Durante seis meses, una serie de caños y paneles fueron removidos mensualmente para estimar el reclutamiento de las especies del macro y microfouling, y fueron sustituidos inmediatamente por caños y paneles limpios. La otra serie de caños y paneles fueron removidas desde el inicio de la exposición en forma acumulativa durante los seis meses, para seguir el desarrollo de la comunidad. Los datos obtenidos de los controles sin cubierta y de los caños y paneles con las cubiertas saturadas de cobre fueron comparados para estimar el comportamiento antifouling de las mismas. Una de las dos cubiertas saturadas de cobre demostró un buen efecto antifouling.

  5. Antifouling coatings: recent developments in the design of surfaces that prevent fouling by proteins, bacteria, and marine organisms

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Indrani; Pangule, Ravindra C.; Kane, Ravi S. [Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Ricketts Building, Troy, NY 12180 (United States)

    2011-02-08

    The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed. Biofouling is of great concern in numerous applications ranging from biosensors to biomedical implants and devices, and from food packaging to industrial and marine equipment. The two major approaches to combat surface fouling are based on either preventing biofoulants from attaching or degrading them. One of the key strategies for imparting adhesion resistance involves the functionalization of surfaces with poly(ethylene glycol) (PEG) or oligo(ethylene glycol). Several alternatives to PEG-based coatings have also been designed over the past decade. While protein-resistant coatings may also resist bacterial attachment and subsequent biofilm formation, in order to overcome the fouling-mediated risk of bacterial infection it is highly desirable to design coatings that are bactericidal. Traditional techniques involve the design of coatings that release biocidal agents, including antibiotics, quaternary ammonium salts (QAS), and silver, into the surrounding aqueous environment. However, the emergence of antibiotic- and silver-resistant pathogenic strains has necessitated the development of alternative strategies. Therefore, other techniques based on the use of polycations, enzymes, nanomaterials, and photoactive agents are being investigated. With regard to marine antifouling coatings, restrictions on the use of biocide-releasing coatings have made the generation of nontoxic antifouling surfaces more important. While considerable progress has been made in the design of antifouling coatings, ongoing research in this area should result in the development of even better antifouling materials in the future. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. In situ observation of the growth of biofouling layer in osmotic membrane bioreactors by multiple fluorescence labeling and confocal laser scanning microscopy.

    Science.gov (United States)

    Yuan, Bo; Wang, Xinhua; Tang, Chuyang; Li, Xiufen; Yu, Guanghui

    2015-05-15

    Since the concept of the osmotic membrane bioreactor (OMBR) was introduced in 2008, it has attracted growing interests for its potential applications in wastewater treatment and reclamation; however, the fouling mechanisms of forward osmosis (FO) membrane especially the development of biofouling layer in the OMBR are not yet clear. Here, the fouled FO membranes were obtained from the OMBRs on days 3, 8 and 25 in sequence, and then the structure and growing rule of the biofouling layer formed on the FO membrane samples were in-situ characterized by multiple fluorescence labeling and confocal laser scanning microscopy (CLSM). CLSM images indicated that the variations in abundance and distribution of polysaccharides, proteins and microorganisms in the biofouling layer during the operation of OMBRs were significantly different. Before the 8th day, their biovolume dramatically increased. Subsequently, the biovolumes of β-d-glucopyranose polysaccharides and proteins continued increasing and leveled off after 8 days, respectively, while the biovolumes of α-d-glucopyranose polysaccharides and microorganisms decreased. Extracellular polymeric substances (EPS) played a significant role in the formation and growth of biofouling layer, while the microorganisms were seldom detected on the upper fouling layer after 3 days. Based on the results obtained in this study, the growth of biofouling layer on the FO membrane surface in the OMBR could be divided into three stages. Initially, EPS was firstly deposited on the FO membrane surface, and then microorganisms associated with EPS located in the initial depositing layer to form clusters. After that, the dramatic increase of the clusters of EPS and microorganisms resulted in the quick growth of biofouling layer during the flux decline of the OMBR. However, when the water flux became stable in the OMBR, some microorganisms and EPS would be detached from the FO membrane surface.

  7. Effect of Surface Coatings on Cylinders Exposed to Underwater Shock

    Directory of Open Access Journals (Sweden)

    Y.W. Kwon

    1994-01-01

    Full Text Available The response of a coated cylinder (metallic cylinder coated with a rubber material subjected to an underwater explosion is analyzed numerically. The dynamic response of the coated cylinder appears to be adversely affected when impacted by an underwater shock wave under certain conditions of geometry and material properties of the coating. When adversely affected, significant deviations in values of axial stress, hoop stress, and strain are observed. The coated cylinder exhibits a larger deformation and higher internal energy in the metallic material. Rubber coatings appeared to inhibit energy dissipation from the metallic material to the surrounding water medium. A parametric study of various coatings was performed on both aluminum and steel cylinders. The adverse effect of the coating decreased when the stiffness of the rubber layer increased, indicating the existence of a threshold value. The results of this study indicate that the stiffness of the coating is a critical factor to the shock hardening of the coated cylinder.

  8. Carbon coatings for medical implants

    Directory of Open Access Journals (Sweden)

    K. Bakowicz-Mitura

    2007-01-01

    Full Text Available Purpose: In this paper we report in vitro and in vivo results of Nanocrystalline Diamond Coatings whichare used in medicine onto medical implants The very important property of carbon coatings is the protectionliving organism against the metalosis. Different medical implants with complicated shapes are covering byNanocrystalline Diamond Coatings by RF dense plasma CVD.Design/methodology/approach: 1 Material characterizations of deposited coatings have been evaluated by using:Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM, Atomic Force Microscopy(AFM, Auger electron spectroscopy (AES, microX-Ray Spectroscopy and bend test 2 Biological investigationbased on: (a in vivo and (b in vitro examinations as well (c clinical investigations – contact allergy.Findings: It was revealed that Nanocrystalline Diamond Coatings form the barrier diffusion between implantand human environment as a consequence prevent leaching of metallic ions into the body. Additionally, theresearch on carbon coatings proved that diamond layers are biocompatible with living organism. Contact allergyon nickel is inhibited by diamond powders.Practical implications: Practical application metal implants with NCD in orthopedy, cardiosurgery, oralsurgery, maxillo-facial surgery and dermatology.Originality/value: We have observed anti-inflammatory, antiallergic and anticancerogenic responses from thecarbon coatings layers onto medical implants like wires and screws.

  9. Hard coatings

    International Nuclear Information System (INIS)

    Hard, wear resistant and low friction coatings are presently produced on a world-wide basis, by different processes such as electrochemical or electroless methods, spray technologies, thermochemical, CVD and PVD. Some of the most advanced processes, especially those dedicated to thin film depositions, basically belong to CVD or PVD technologies, and will be looked at in more detail. The hard coatings mainly consist of oxides, nitrides, carbides, borides or carbon. Over the years, many processes have been developed which are variations and/or combinations of the basic CVD and PVD methods. The main difference between these two families of deposition techniques is that the CVD is an elevated temperature process (≥ 700 C), while the PVD on the contrary, is rather a low temperature process (≤ 500 C); this of course influences the choice of substrates and properties of the coating/substrate systems. Fundamental aspects of the vapor phase deposition techniques and some of their influences on coating properties will be discussed, as well as the very important interactions between deposit and substrate: diffusions, internal stress, etc. Advantages and limitations of CVD and PVD respectively will briefly be reviewed and examples of applications of the layers will be given. Parallel to the development and permanent updating of surface modification technologies, an effort was made to create novel characterisation methods. A close look will be given to the coating adherence control by means of the scratch test, at the coating hardness measurement by means of nanoindentation, at the coating wear resistance by means of a pin-on-disc tribometer, and at the surface quality evaluation by Atomic Force Microscopy (AFM). Finally, main important trends will be highlighted. (orig.)

  10. Marine bio-fouling of different alloys exposed to continuous flowing fresh seawater by electrochemical impedance spectroscopy

    OpenAIRE

    Khalid Al-Muhanna; Khaled Habib

    2016-01-01

    The petroleum industry and desalination plants suffer from marine bio-fouling problems that have a major role in the stimulation of the corrosion process. Thus, the aim of this study was to investigate the effect of the micro and the macro-organisms, on the corrosion behavior of different alloys used in Kuwait’s industries. The alloys used in this study were; sanicro 28, stainless steel 316L, Cu–Ni 70–30, and titanium. The electrochemical impedance spectroscopy was used in this study in order...

  11. The biocompatibility and anti-biofouling properties of magnetic core-multishell Fe@C NWs-AAO nanocomposites.

    Science.gov (United States)

    Lindo, André M; Pellicer, Eva; Zeeshan, Muhammad A; Grisch, Roman; Qiu, Famin; Sort, Jordi; Sakar, Mahmut S; Nelson, Bradley J; Pané, Salvador

    2015-05-28

    Soft-magnetic core-multishell Fe@C NWs-AAO nanocomposites were synthesized using anodization, electrodeposition and low-pressure chemical vapour deposition (CVD) at 900 °C. High chemical and mechanical stability is achieved by the conversion from amorphous to θ- and δ-Al2O3 phases above 600 °C. Moreover, the surface properties of the material evolve from bioactive, for porous AAO, to bioinert, for Fe@C NW filled AAO nanocomposite. Although the latter is not cytotoxic, cells do not adhere onto the surface of the magnetic nanocomposite, thus proving its anti-biofouling character.

  12. Plastics for corrosion inhibition

    CERN Document Server

    Goldade, Victor A; Makarevich, Anna V; Kestelman, Vladimir N

    2005-01-01

    The development of polymer composites containing inhibitors of metal corrosion is an important endeavour in modern materials science and technology. Corrosion inhibitors can be located in a polymer matrix in the solid, liquid or gaseous phase. This book details the thermodynamic principles for selecting these components, their compatibility and their effectiveness. The various mechanisms of metal protection – barrier, inhibiting and electromechanical – are considered, as are the conflicting requirements placed on the structure of the combined material. Two main classes of inhibited materials (structural and films/coatings) are described in detail. Examples are given of structural plastics used in friction units subjected to mechano-chemical wear and of polymer films/coatings for protecting metal objects against corrosion.

  13. Probing biofouling resistant polymer brush surfaces by atomic force microscopy based force spectroscopy.

    Science.gov (United States)

    Schön, Peter; Kutnyanszky, Edit; ten Donkelaar, Bas; Santonicola, M Gabriella; Tecim, Tugba; Aldred, Nick; Clare, Anthony S; Vancso, G Julius

    2013-02-01

    The protein repellency and biofouling resistance of zwitterionic poly(sulfobetaine methacrylate)(pSBMA) brushes grafted via surface initiated polymerization (SIP) from silicon and glass substrata was assessed using atomic force microscopy (AFM) adherence experiments. Laboratory settlement assays were conducted with cypris larvae of the barnacle Balanus amphitrite. AFM adherence includes the determination of contact rupture forces when AFM probe tips are withdrawn from the substratum. When the surface of the AFM tip is modified, adherence can be assessed with chemical specifity using a method known as chemical force microscopy (CFM). In this study, AFM tips were chemically functionalized with (a) fibronectin- here used as model for a nonspecifically adhering protein - and (b) arginine-glycine-aspartic acid (RGD) peptide motifs covalently attached to poly(methacrylic acid) (PMAA) brushes as biomimics of cellular adhesion receptors. Fibronectin functionalized tips showed significantly reduced nonspecific adhesion to pSBMA-modified substrata compared to bare gold (2.3±0.75 nN) and octadecanethiol (ODT) self-assembled monolayers (1.3±0.75 nN). PMAA and PMAA-RGD modified probes showed no significant adhesion to pSBMA modified silicon substrata. The results gathered through AFM protein adherence studies were complemented by laboratory fouling studies, which showed no adhesion of cypris larvae of Balanus amphitrite on pSBMA. With regard to its unusually high non-specific adsorption to a wide variety of materials the behavior of fibronectin is analogous to the barnacle cyprid temporary adhesive that also binds well to surfaces differing in polarity, charge and free energy. The antifouling efficacy of pSBMA may, therefore, be directly related to the ability of this surface to resist nonspecific protein adsorption. PMID:23138001

  14. Bacteriophage therapy for membrane biofouling in membrane bioreactors and antibiotic-resistant bacterial biofilms.

    Science.gov (United States)

    Bhattacharjee, Ananda Shankar; Choi, Jeongdong; Motlagh, Amir Mohaghegh; Mukherji, Sachiyo T; Goel, Ramesh

    2015-08-01

    To demonstrate elimination of bacterial biofilm on membranes to represent wastewater treatment as well as biofilm formed by antibiotic-resistant bacterial (ARB) to signify medical application, an antibiotic-resistant bacterium and its lytic bacteriophage were isolated from a full-scale wastewater treatment plant. Based on gram staining and complete 16 S rDNA sequencing, the isolated bacterium showed a more than 99% homology with Delftia tsuruhatensis, a gram-negative bacterium belonging to β-proteobacteria. The Delftia lytic phage's draft genome revealed the phage to be an N4-like phage with 59.7% G + C content. No transfer RNAs were detected for the phage suggesting that the phage is highly adapted to its host Delftia tsuruhatensis ARB-1 with regard to codon usage, and does not require additional tRNAs of its own. The gene annotation of the Delftia lytic phage found three different components of RNA polymerase (RNAP) in the genome, which is a typical characteristic of N4-like phages. The lytic phage specific to D. tsuruhatensis ARB-1 could successfully remove the biofilm formed by it on a glass slide. The water flux through the membrane of a prototype lab-scale membrane bioreactor decreased from 47 L/h m(2) to ∼15 L/h m(2) over 4 days due to a biofilm formed by D. tsuruhatensis ARB-1. However, the flux increased to 70% of the original after the lytic phage application. Overall, this research demonstrated phage therapy's great potential to solve the problem of membrane biofouling, as well as the problems posed by pathogenic biofilms in external wounds and on medical instruments.

  15. Distinctive colonization of Bacillus sp. bacteria and the influence of the bacterial biofilm on electrochemical behaviors of aluminum coatings.

    Science.gov (United States)

    Abdoli, Leila; Suo, Xinkun; Li, Hua

    2016-09-01

    Formation of biofilm is usually essential for the development of biofouling and crucially impacts the corrosion of marine structures. Here we report the attachment behaviors of Bacillus sp. bacteria and subsequent formation of bacterial biofilm on stainless steel and thermal sprayed aluminum coatings in artificial seawater. The colonized bacteria accelerate the corrosion of the steel plates, and markedly enhance the anti-corrosion performances of the Al coatings in early growth stage of the bacterial biofilm. After 7days incubation, the biofilm formed on the steel is heterogeneous while exhibits homogeneous feature on the Al coating. Atomic force microscopy examination discloses inception of formation of local pitting on steel plates associated with significantly roughened surface. Electrochemical testing suggests that the impact of the bacterial biofilm on the corrosion behaviors of marine structures is not decided by the biofilm alone, it is instead attributed to synergistic influence by both the biofilm and physicochemical characteristics of the substratum materials.

  16. Distinctive colonization of Bacillus sp. bacteria and the influence of the bacterial biofilm on electrochemical behaviors of aluminum coatings.

    Science.gov (United States)

    Abdoli, Leila; Suo, Xinkun; Li, Hua

    2016-09-01

    Formation of biofilm is usually essential for the development of biofouling and crucially impacts the corrosion of marine structures. Here we report the attachment behaviors of Bacillus sp. bacteria and subsequent formation of bacterial biofilm on stainless steel and thermal sprayed aluminum coatings in artificial seawater. The colonized bacteria accelerate the corrosion of the steel plates, and markedly enhance the anti-corrosion performances of the Al coatings in early growth stage of the bacterial biofilm. After 7days incubation, the biofilm formed on the steel is heterogeneous while exhibits homogeneous feature on the Al coating. Atomic force microscopy examination discloses inception of formation of local pitting on steel plates associated with significantly roughened surface. Electrochemical testing suggests that the impact of the bacterial biofilm on the corrosion behaviors of marine structures is not decided by the biofilm alone, it is instead attributed to synergistic influence by both the biofilm and physicochemical characteristics of the substratum materials. PMID:27289310

  17. Nanostructured Coatings

    Science.gov (United States)

    Rivière, J.-P.

    In many branches of technology where surfaces are playing a growing role, the use of coatings is often the only way to provide surfaces with specific functional properties. For example, the austenitic stainless steels or titanium alloys exhibit poor resistance to wear and low hardness values, which limits the field of applications. The idea then is to develop new solutions which would improve the mechanical performance and durability of objects used in contact and subjected to mechanical forces in hostile gaseous or liquid environments. Hard coatings are generally much sought after to enhance the resistance to wear and corrosion. They are of particular importance because they constitute a class of protective coatings which is already widely used on an industrial scale to improve the hardness and lifetime of cutting tools.

  18. Organoselenium Surface Modification of Stainless Steel Surfaces To Prevent Biofouling in Treatment of Space Wastestreams Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this work is to quantify the reduction of biofilm formation in a water distribution system resulting from an organoselenium surface coating on...

  19. Evidence of compositional and ultrastructural shifts during the development of calcareous tubes in the biofouling tubeworm, Hydroides elegans.

    Science.gov (United States)

    Chan, Vera Bin San; Vinn, Olev; Li, Chaoyi; Lu, Xingwen; Kudryavtsev, Anatoliy B; Schopf, J William; Shih, Kaimin; Zhang, Tong; Thiyagarajan, Vengatesen

    2015-03-01

    The serpulid tubeworm, Hydroides elegans, is an ecologically and economically important species whose biology has been fairly well studied, especially in the context of larval development and settlement on man-made objects (biofouling). Nevertheless, ontogenetic changes associated with calcareous tube composition and structures have not yet been studied. Here, the ultrastructure and composition of the calcareous tubes built by H. elegans was examined in the three early calcifying juvenile stages and in the adult using XRD, FTIR, ICP-OES, SEM and Raman spectroscopy. Ontogenetic shifts in carbonate mineralogy were observed, for example, juvenile tubes contained more amorphous calcium carbonate and were predominantly aragonitic whereas adult tubes were bimineralic with considerably more calcite. The mineral composition gradually shifted during the tube development as shown by a decrease in Sr/Ca and an increase of Mg/Ca ratios with the tubeworm's age. The inner tube layer contained calcite, whereas the outer layer contained aragonite. Similarly, the tube complexity in terms of ultrastructure was associated with development. The sequential appearance of unoriented ultrastructures followed by oriented ultrastructures may reflect the evolutionary history of serpulid tube biominerals. As aragonitic structures are more susceptible to dissolution under ocean acidification (OA) conditions but are more difficult to be removed by anti-fouling treatments, the early developmental stages of the tubeworms may be vulnerable to OA but act as the important target for biofouling control. PMID:25600412

  20. Fine-Tuning the Surface of Forward Osmosis Membranes via Grafting Graphene Oxide: Performance Patterns and Biofouling Propensity.

    Science.gov (United States)

    Hegab, Hanaa M; ElMekawy, Ahmed; Barclay, Thomas G; Michelmore, Andrew; Zou, Linda; Saint, Christopher P; Ginic-Markovic, Milena

    2015-08-19

    Graphene oxide (GO) nanosheets were attached to the polyamide selective layer of thin film composite (TFC) forward osmosis (FO) membranes through a poly L-Lysine (PLL) intermediary using either layer-by-layer or hybrid (H) grafting strategies. Fourier transform infrared spectroscopy, zeta potential, and thermogravimetric analysis confirmed the successful attachment of GO/PLL, the surface modification enhancing both the hydrophilicity and smoothness of the membrane's surface demonstrated by water contact angle, atomic force microscopy, and transmission electron microscopy. The biofouling resistance of the FO membranes determined using an adenosine triphosphate bioluminescence test showed a 99% reduction in surviving bacteria for GO/PLL-H modified membranes compared to pristine membrane. This antibiofouling property of the GO/PLL-H modified membrane was reflected in reduced flux decline compared to all other samples when filtering brackish water under biofouling conditions. Further, the high density and tightly bound GO nanosheets using the hybrid modification reduced the reverse solute flux compared to the pristine, which reflects improved membrane selectivity. These results illustrate that the GO/PLL-H modification is a valuable addition to improve the performance of FO TFC membranes.

  1. Desiccation as a mitigation tool to manage biofouling risks: trials on temperate taxa to elucidate factors influencing mortality rates.

    Science.gov (United States)

    Hopkins, Grant A; Prince, Madeleine; Cahill, Patrick L; Fletcher, Lauren M; Atalah, Javier

    2016-01-01

    The desiccation tolerance of biofouling taxa (adults and early life-stages) was determined under both controlled and 'realistic' field conditions. Adults of the ascidian Ciona spp. died within 24 h. Mortality in the adult blue mussel Mytilus galloprovincialis occurred within 11 d under controlled conditions, compared with 7 d when held outside. The Pacific oyster Crassostrea gigas was the most desiccation-tolerant taxon tested (up to 34 d under controlled conditions). Biofouling orientated to direct sunlight showed faster mortality rates for all the taxa tested. Mortality in Mytilus juveniles took up to 24 h, compared with 8 h for Ciona, with greater survival at the higher temperature (18.5°C) and humidity (~95% RH) treatment combination. This study demonstrated that desiccation can be an effective mitigation method for a broad range of fouling taxa, especially their early life-stages. Further work is necessary to assess risks from other high-risk species such as algae and cyst forming species.

  2. Evidence of compositional and ultrastructural shifts during the development of calcareous tubes in the biofouling tubeworm, Hydroides elegans.

    Science.gov (United States)

    Chan, Vera Bin San; Vinn, Olev; Li, Chaoyi; Lu, Xingwen; Kudryavtsev, Anatoliy B; Schopf, J William; Shih, Kaimin; Zhang, Tong; Thiyagarajan, Vengatesen

    2015-03-01

    The serpulid tubeworm, Hydroides elegans, is an ecologically and economically important species whose biology has been fairly well studied, especially in the context of larval development and settlement on man-made objects (biofouling). Nevertheless, ontogenetic changes associated with calcareous tube composition and structures have not yet been studied. Here, the ultrastructure and composition of the calcareous tubes built by H. elegans was examined in the three early calcifying juvenile stages and in the adult using XRD, FTIR, ICP-OES, SEM and Raman spectroscopy. Ontogenetic shifts in carbonate mineralogy were observed, for example, juvenile tubes contained more amorphous calcium carbonate and were predominantly aragonitic whereas adult tubes were bimineralic with considerably more calcite. The mineral composition gradually shifted during the tube development as shown by a decrease in Sr/Ca and an increase of Mg/Ca ratios with the tubeworm's age. The inner tube layer contained calcite, whereas the outer layer contained aragonite. Similarly, the tube complexity in terms of ultrastructure was associated with development. The sequential appearance of unoriented ultrastructures followed by oriented ultrastructures may reflect the evolutionary history of serpulid tube biominerals. As aragonitic structures are more susceptible to dissolution under ocean acidification (OA) conditions but are more difficult to be removed by anti-fouling treatments, the early developmental stages of the tubeworms may be vulnerable to OA but act as the important target for biofouling control.

  3. Fine-Tuning the Surface of Forward Osmosis Membranes via Grafting Graphene Oxide: Performance Patterns and Biofouling Propensity.

    Science.gov (United States)

    Hegab, Hanaa M; ElMekawy, Ahmed; Barclay, Thomas G; Michelmore, Andrew; Zou, Linda; Saint, Christopher P; Ginic-Markovic, Milena

    2015-08-19

    Graphene oxide (GO) nanosheets were attached to the polyamide selective layer of thin film composite (TFC) forward osmosis (FO) membranes through a poly L-Lysine (PLL) intermediary using either layer-by-layer or hybrid (H) grafting strategies. Fourier transform infrared spectroscopy, zeta potential, and thermogravimetric analysis confirmed the successful attachment of GO/PLL, the surface modification enhancing both the hydrophilicity and smoothness of the membrane's surface demonstrated by water contact angle, atomic force microscopy, and transmission electron microscopy. The biofouling resistance of the FO membranes determined using an adenosine triphosphate bioluminescence test showed a 99% reduction in surviving bacteria for GO/PLL-H modified membranes compared to pristine membrane. This antibiofouling property of the GO/PLL-H modified membrane was reflected in reduced flux decline compared to all other samples when filtering brackish water under biofouling conditions. Further, the high density and tightly bound GO nanosheets using the hybrid modification reduced the reverse solute flux compared to the pristine, which reflects improved membrane selectivity. These results illustrate that the GO/PLL-H modification is a valuable addition to improve the performance of FO TFC membranes. PMID:26214126

  4. Graphene-coated hollow fiber membrane as the cathode in anaerobic electrochemical membrane bioreactors – Effect of configuration and applied voltage on performance and membrane fouling

    KAUST Repository

    Werner, Craig

    2015-12-22

    Electrically conductive, graphene-coated hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 V and 0.9 V) using a new rectangular reactor configuration, compared to a previous tubular design (0.7 V). The onset of biofouling was delayed and minimized in rectangular reactors operated at 0.9 V, compared to those at 0.7 V due to higher rates of hydrogen production. Maximum transmembrane pressures for the rectangular reactor were only 0.10 bar (0.7 V) or 0.05 bar (0.9 V) after 56 days of operation, compared to 0.46 bar (0.7 V) for the tubular reactor after 52 days. The thickness of the membrane biofouling layer was approximately 0.4 µm for rectangular reactors and 4 µm for the tubular reactor. Higher permeate quality (TSS = 0.05 mg/L) was achieved in the rectangular AnEMBR than the tubular AnEMBR (TSS = 17 mg/L), likely due to higher current densities that minimized the accumulation of cells in suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

  5. Compositional Similarities and Differences between Transparent Exopolymer Particles (TEP) from two Marine Bacteria and two Marine Algae: Significance to Surface Biofouling

    KAUST Repository

    Li, Sheng

    2015-06-12

    Transparent-exopolymer-particles (TEP) have been recently identified as a significant contributor to surface biofouling, such as on reverse osmosis (RO) membranes. TEP research has mainly focused on algal TEP/TEP precursors while limited investigations have been conducted on those released by bacteria. In this study, TEP/TEP precursors derived from both algae and bacteria were isolated and then characterized to investigate their similarities and/or differences using various advanced analytical techniques, thus providing a better understanding of their potential effect on biofouling. Bacterial TEP/TEP precursors were isolated from two species of marine bacteria (Pseudidiomarina homiensis and Pseudoalteromonas atlantica) while algal TEP/TEP precursors were isolated from two marine algae species (Alexandrium tamarense and Chaetoceros affinis). Results indicated that both isolated bacterial and algal TEP/TEP precursors were associated with protein-like materials, and most TEP precursors were high-molecular-weight biopolymers. Furthermore all investigated algal and bacterial TEP/TEP precursors showed a lectin-like property, which can enable them to act as a chemical conditioning layer and to agglutinate bacteria. This property may enhance surface biofouling. However, both proton nuclear magnetic resonance (NMR) spectra and the nitrogen/carbon (N/C) ratios suggested that the algal TEP/TEP precursors contained much less protein content than the bacterial TEP/TEP precursors. This difference may influence their initial deposition and further development of surface biofouling.

  6. Photodegradation mechanisms of TPB coatings

    Science.gov (United States)

    VanGemert, J. K.

    2013-10-01

    In these proceedings I discuss results of a degradation mechanism study of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments. Using gas chromatography coupled to mass spectrometry (GCMS) we identified the UV blocking impurity benzophenone. We monitored the drop in performance and increase of benzophenone concentration in TPB plates with exposure to ultraviolet (UV) light, and demonstrate the correlation between these two variables. We show promisng results obtained by adding a free radical inhibiting stabilizing compound, which improves the initial performance of light-guide coatings by up to 20% and significantly improves their UV stability. These proceedings summarize work previously published in JINST [1].

  7. Deposition parameters to improve the fouling-release properties of thin siloxane coatings prepared by PACVD

    International Nuclear Information System (INIS)

    A range of SiOx-like coatings was deposited on glass slides from a hexamethylsiloxane precursor by plasma-assisted CVD. The effect of varying deposition parameters, specifically ion cleaning time and HMDSO/O2 ratios, on the coating properties and antifouling performance was investigated. At low HMDSO/O2 ratios, the resulting coatings were close to SiO2. Carbon content in the bulk of the coatings increased with increasing HMDSO/O2 ratio. Coatings deposited at high HMDSO/O2 ratios and with the longest cleaning time (30 min), elevated the relative carbon content to 25 atomic %. Surface energies (22-43 mJ/m) were correlated with the degree of surface oxidation and hydrocarbon content. With the exception of the most polar coatings the apolar component of the surface energy (γLW) was the dominant component. In the most hydrophilic coatings, the Lewis base component of the surface energy (γ-) was dominant. Significantly improved antifouling performance was detected with the most reduced coatings deposited using the extended ion cleaning times. For both, the removal of sporelings of the marine green alga, Ulvalinza and the initial adhesion of the freshwater bacterium, Pseudomonas fluorescens, there was a strong, positive correlation between strength of attachment and ion cleaning time. Increased ion cleaning time will elevate the deposition temperature, increasing decomposition rates and thus the crosslinking of the polymer. Increased cross-linking may render these coatings less permeable to penetration and mechanical interlocking by the adhesive polymers used by these organisms, thus reducing their adhesion. Films with improved biological performance have potential for use as coatings in the control of biofouling in applications such as heat exchangers, where thin films are important for effective thermal transfer, or optical windows where transparency is important.

  8. Biocompatible PEDOT:Nafion composite electrode coatings for selective detection of neurotransmitters in vivo.

    Science.gov (United States)

    Vreeland, Richard F; Atcherley, Christopher W; Russell, Wilfred S; Xie, Jennifer Y; Lu, Dong; Laude, Nicholas D; Porreca, Frank; Heien, Michael L

    2015-03-01

    A Nafion and poly(3,4-ethylenedioxythiophene) (PEDOT) containing composite polymer has been electropolymerized on carbon-fiber microelectrodes with the goal of creating a mechanically stable, robust, and controllable electrode coating that increases the selectivity and sensitivity of in vivo electrochemical measurements. The coating is deposited on carbon-fiber microelectrodes by applying a triangle waveform from +1.5 V to -0.8 V and back in a dilute solution of ethylenedioxythiophene (EDOT) and Nafion in acetonitrile. Scanning electron microscopy demonstrated that the coating is uniform and ∼100 nm thick. Energy-dispersive X-ray spectroscopy demonstrated that both sulfur and fluorine are present in the coating, indicating the incorporation of PEDOT (poly(3,4-ethylenedioxythiophene) and Nafion. Two types of PEDOT:Nafion coated electrodes were then analyzed electrochemically. PEDOT:Nafion-coated electrodes made using 200 μM EDOT exhibit a 10-90 response time of 0.46 ± 0.09 s versus 0.45 ± 0.11 s for an uncoated fiber in response to a 1.0 μM bolus of dopamine. The electrodes coated using a higher EDOT concentration (400 μM) are slower with a 10-90 response time of 0.84 ± 0.19 s, but display increased sensitivity to dopamine, at 46 ± 13 nA/μM, compared to 26 ± 6 nA/μM for the electrodes coated in 200 μM EDOT and 13 ± 2 nA/μM for an uncoated fiber. PEDOT:Nafion-coated electrodes were lowered into the nucleus accumbens of a rat, and both spontaneous and electrically evoked dopamine release were measured. In addition to improvements in sensitivity and selectivity, the coating dramatically reduces acute in vivo biofouling. PMID:25692657

  9. Deposition parameters to improve the fouling-release properties of thin siloxane coatings prepared by PACVD

    Energy Technology Data Exchange (ETDEWEB)

    Akesso, Laurent; Navabpour, Parnia; Teer, Dennis [TEER Coatings Ltd, West Stone House, Berry Hill Industrial Estate, Droitwich, Worcestershire, WR9 9AS (United Kingdom); Pettitt, Michala E.; Callow, Maureen E. [School of Biosciences, University of Birmingham, Birmingham B15 2TT (United Kingdom); Liu Chen; Su Xueju; Wang Su; Zhao Qi [Department of Mechanical Engineering, University of Dundee (United Kingdom); Donik, Crtomir; Kocijan, Aleksandra; Jenko, Monika [Institute of Metals and Technology, Lepi pot 11, p.p. 431, SI-1001 Ljubljana (Slovenia); Callow, James A., E-mail: j.a.callow@bham.ac.uk [School of Biosciences, The University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2009-04-15

    A range of SiO{sub x}-like coatings was deposited on glass slides from a hexamethylsiloxane precursor by plasma-assisted CVD. The effect of varying deposition parameters, specifically ion cleaning time and HMDSO/O{sub 2} ratios, on the coating properties and antifouling performance was investigated. At low HMDSO/O{sub 2} ratios, the resulting coatings were close to SiO{sub 2}. Carbon content in the bulk of the coatings increased with increasing HMDSO/O{sub 2} ratio. Coatings deposited at high HMDSO/O{sub 2} ratios and with the longest cleaning time (30 min), elevated the relative carbon content to 25 atomic %. Surface energies (22-43 mJ/m) were correlated with the degree of surface oxidation and hydrocarbon content. With the exception of the most polar coatings the apolar component of the surface energy ({gamma}{sup LW}) was the dominant component. In the most hydrophilic coatings, the Lewis base component of the surface energy ({gamma}{sup -}) was dominant. Significantly improved antifouling performance was detected with the most reduced coatings deposited using the extended ion cleaning times. For both, the removal of sporelings of the marine green alga, Ulvalinza and the initial adhesion of the freshwater bacterium, Pseudomonas fluorescens, there was a strong, positive correlation between strength of attachment and ion cleaning time. Increased ion cleaning time will elevate the deposition temperature, increasing decomposition rates and thus the crosslinking of the polymer. Increased cross-linking may render these coatings less permeable to penetration and mechanical interlocking by the adhesive polymers used by these organisms, thus reducing their adhesion. Films with improved biological performance have potential for use as coatings in the control of biofouling in applications such as heat exchangers, where thin films are important for effective thermal transfer, or optical windows where transparency is important.

  10. Potassium-dependent assembly of coated pits: new coated pits form as planar clathrin lattices

    OpenAIRE

    1986-01-01

    Previous studies have shown that when human fibroblasts are depleted of intracellular K+, coated pits disappear from the cell surface and the receptor-mediated endocytosis of low density lipoprotein (LDL) is inhibited. We have now used the K+ depletion protocol to study several aspects of coated pit function. First, since coated pits rapidly form when K+-depleted fibroblasts are incubated in the presence of 10 mM KCl, we studied the sequence of assembly of coated pits as visualized in carbon-...

  11. Structures and antifouling properties of low surface energy non-toxic antifouling coatings modified by nano-SiO2 powder

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Antifouling coatings are used to improve the speed and energy efficiency of ships by preventing or- ganisms, such as barnacles and weed, building up on the underwater hull and helping the ships movement through the water. Typically, marine coatings are tributyltin self-polishing copolymer paints containing toxic molecules called biocides. They have been the most successful in combating bio- fouling on ships, but their widespread use has caused severe pollution in the marine ecosystem. The low surface energy marine coating is an entirely non-toxic alternative, which reduces the adhesion strength of marine organisms, facilitating their hydrodynamic removal at high speeds. In this paper, the novel low surface energy non-toxic marine antifouling coatings were prepared with modified acrylic resin, nano-SiO2, and other pigments. The effects of nano-SiO2 on the surface structure and elastic modulus of coating films have been studied, and the seawater test has been carried out in the Dalian Bay. The results showed that micro-nano layered structures on the coating films and the lowest surface energy and elastic modulus could be obtained when an appropriate mass ratio of resin, nano-SiO2, and other pigments in coatings approached. The seawater exposure test has shown that the lower the sur- face energy and elastic modulus of coatings are, the less the marine biofouling adheres on the coating films.

  12. Multiple GTP-binding proteins participate in clathrin-coated vesicle- mediated endocytosis

    OpenAIRE

    1993-01-01

    We have examined the effects of various agonists and antagonists of GTP- binding proteins on receptor-mediated endocytosis in vitro. Stage- specific assays which distinguish coated pit assembly, invagination, and coat vesicle budding have been used to demonstrate requirements for GTP-binding protein(s) in each of these events. Coated pit invagination and coated vesicle budding are both stimulated by addition of GTP and inhibited by GDP beta S. Although coated pit invagination is resistant to ...

  13. 2D Gel-Based Multiplexed Proteomic Analysis during Larval Development and Metamorphosis of the Biofouling Polychaete Tubeworm Hydroides elegans

    KAUST Repository

    Zhang, Yu

    2010-09-03

    Larval settlement and metamorphosis of a common biofouling polychaete worm, Hydroides elegans, involve remarkable structural and physiological changes during this pelagic to sessile habitat shift. The endogenous protein molecules and post-translational modifications that drive this larval transition process are not only of interest to ecologists but also to the antifouling paint industry, which aims to control the settlement of this biofouling species on man-made structures (e.g., ship hulls). On the basis of our recent proteomic studies, we hypothesize that rapid larval settlement of H. elegans could be mediated through changes in phosphorylation status of proteins rather than extensive de novo synthesis of proteins. To test this hypothesis, 2D gel-based multiplexed proteomics technology was used to monitor the changes in protein expression and phosphorylation status during larval development and metamorphosis of H. elegans. The protein expression profiles of larvae before and after they reached competency to attach and metamorphose were similar in terms of major proteins, but the percentage of phosphorylated proteins increased from 41% to 49% after competency. Notably, both the protein and phosphoprotein profiles of the metamorphosed individuals (adult) were distinctly different from that of the larvae, with only 40% of the proteins phosphorylated in the adult stage. The intensity ratio of all phosphoprotein spots to all total protein spots was also the highest in the competent larval stage. Overall, our results indicated that the level of protein phosphorylation might play a crucial role in the initiation of larval settlement and metamorphosis. © 2010 American Chemical Society.

  14. Biofouling of reverse-osmosis membranes under different shear rates during tertiary wastewater desalination: microbial community composition.

    Science.gov (United States)

    Al Ashhab, Ashraf; Gillor, Osnat; Herzberg, Moshe

    2014-12-15

    We investigated the influence of feed-water shear rate during reverse-osmosis (RO) desalination on biofouling with respect to microbial community composition developed on the membrane surface. The RO membrane biofilm's microbial community profile was elucidated during desalination of tertiary wastewater effluent in a flat-sheet lab-scale system operated under high (555.6 s(-1)), medium (370.4 s(-1)), or low (185.2 s(-1)) shear rates, corresponding to average velocities of 27.8, 18.5, and 9.3 cm s(-1), respectively. Bacterial diversity was highest when medium shear was applied (Shannon-Weaver diversity index H' = 4.30 ± 0.04) compared to RO-membrane biofilm developed under lower and higher shear rates (H' = 3.80 ± 0.26 and H' = 3.42 ± 0.38, respectively). At the medium shear rate, RO-membrane biofilms were dominated by Betaproteobacteria, whereas under lower and higher shear rates, the biofilms were dominated by Alpha- and Gamma- Proteobacteria, and the latter biofilms also contained Deltaproteobacteria. Bacterial abundance on the RO membrane was higher at low and medium shear rates compared to the high shear rate: 8.97 × 10(8) ± 1.03 × 10(3), 4.70 × 10(8) ± 1.70 × 10(3) and 5.72 × 10(6) ± 2.09 × 10(3) copy number per cm(2), respectively. Interestingly, at the high shear rate, the RO-membrane biofilm's bacterial community consisted mainly of populations known to excrete high amounts of extracellular polymeric substances. Our results suggest that the RO-membrane biofilm's community composition, structure and abundance differ in accordance with applied shear rate. These results shed new light on the biofouling phenomenon and are important for further development of antibiofouling strategies for RO membranes.

  15. Biofouling potential reductions using a membrane hybrid system as a pre-treatment to seawater reverse osmosis.

    Science.gov (United States)

    Jeong, Sanghyun; Kim, Lan Hee; Kim, Sung-Jo; Nguyen, Tien Vinh; Vigneswaran, Saravanamuthu; Kim, In S

    2012-07-01

    Biofouling on reverse osmosis (RO) membranes is the most serious problem which affects desalination process efficiency and increases operation cost. The biofouling cannot be effectively removed by the conventional pre-treatment traditionally used in desalination plants. Hybrid membrane systems coupling the adsorption and/or coagulation with low-pressure membranes can be a sustainable pre-treatment in reducing membrane fouling and at the same time improving the feed water quality to the seawater reverse osmosis. The addition of powder activated carbon (PAC) of 1.5 g/L into submerged membrane system could help to remove significant amount of both hydrophobic compounds (81.4%) and hydrophilic compounds (73.3%). When this submerged membrane adsorption hybrid system (SMAHS) was combined with FeCl(3) coagulation of 0.5 mg of Fe(3+)/L, dissolved organic carbon removal efficiency was excellent even with lower dose of PAC (0.5 g/L). Detailed microbial studies conducted with the SMAHS and the submerged membrane coagulation-adsorption hybrid system (SMCAHS) showed that these hybrid systems can significantly remove the total bacteria which contain also live cells. As a result, microbial adenosine triphosphate (ATP) as well as total ATP concentrations in treated seawater and foulants was considerably decreased. The bacteria number in feed water prior to RO reduced from 5.10E(+06) cells/mL to 3.10E(+03) cells/mL and 9.30E(+03) cells/mL after SMAHS and SMCAHS were applied as pre-treatment, respectively. These led to a significant reduction of assimilable organic carbon (AOC) by 10.1 μg/L acetate-C when SMCAHS was used as a pre-treatment after 45-h RO operation. In this study, AOC method was modified to measure the growth of bacteria in seawater by using the Pseudomonas P.60 strain.

  16. Corrosion resistant coating

    Science.gov (United States)

    Wrobleski, Debra A.; Benicewicz, Brian C.; Thompson, Karen G.; Bryan, Coleman J.

    1997-01-01

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  17. Eliminación del Biofouling en intercambiadores de calor-condensadores que minimicen el impacto ambiental en el medio marino

    OpenAIRE

    Río Calonge, Belén

    2011-01-01

    RESUMEN: La presente tesis doctoral tiene por objeto tratar de eliminar el fenómeno no deseable de formación de biofouling en diferentes superficies tubulares de intercambiadores de calor, mediante tratamientos físicos y químicos, intentando minimizar el impacto ambiental creado en los efluentes de las instalaciones industriales. El equipo experimental está compuesto por una planta piloto de intercambiadores de calor condensadores dotada de ocho tubos que funcionan como sistemas independie...

  18. Graphene Coatings

    DEFF Research Database (Denmark)

    Stoot, Adam Carsten; Camilli, Luca; Bøggild, Peter

    2014-01-01

    Owing to its remarkable electrical and mechanical properties, graphene has been attracting tremendous interest in materials science. In particular, its chemical stability and impermeability make it a promising protective membrane. However, recent investigations reveal that single layer graphene...... cannot be used as a barrier in the long run, due to galvanic corrosion phenomena arising when oxygen or water penetrate through graphene cracks or domain boundaries. Here, we overcome this issue by using a multilayered (ML) graphene coating. Our lab- as well as industrial-scale tests demonstrate that ML...... graphene can effectively protect Ni in harsh environments, even after long term exposure. This is made possible by the presence of a high number of graphene layers, which can efficiently mask the cracks and domain boundaries defects found in individual layers of graphene. Our findings thus show...

  19. Application of Ketone-Based Resins as Anticorrosive Coating

    OpenAIRE

    Esma Sezer; Nilgün Kızılcan; Kerim Çoban

    2011-01-01

    Effect of some newly synthesized modified ketonic resins on corrosion inhibition of stainless steel (SS) and copper (Cu) was investigated in acidic medium. Carboxyl, hydroxyl, and carbonyl functionalized resins have been coated on metal electrode as a thin film by dipping method. Corrosion characteristics of coating on SS (304 L) and Cu were investigated by polarization, open-circuit, and impedance measurement. These measurements performed at different time and the stability of polymeric coat...

  20. 非氧化杀菌剂控制反渗透系统生物污染%Non-oxidative Biocide for Control of Biofouling in RO Systems

    Institute of Scientific and Technical Information of China (English)

    苏立永; 潘献辉; 葛云红; 王晓玲

    2012-01-01

    生物污染是反渗透(RO)系统运行过程中最常见和最严重的问题之一,它限制了膜技术在处理富含微生物源水上的应用.探讨了RO系统生物污染的形成过程,对生物污染的不同控制方法进行了比较,分析了非氧化杀菌剂DBNPA的性能,并介绍了在含微生物源水的RO系统中DBNPA控制生物污染的应用实例.%Biofouling is one of the most common and severe problems during the operation of RO system. It restricts the application of membrane technology in treatment of water sources containing abundant microorganisms. The process of biofouling formation in RO system was discussed, and different methods of biofouling control were compared, and the disinfection performance of DBNPA was analyzed. An example of DBNPA applied in RO raw water containing abundant microorganisms was given.

  1. Microstructural aspects of zirconia thermal barrier coatings

    Science.gov (United States)

    Mitchell, T. E.; Suhr, D. S.; Keller, R. J.; Lanteri, V.; Heuer, A. H.

    1985-01-01

    Various combination of plasma-sprayed bond coatings and zirconia ceramic coatings on a nickel-based superalloy substrate were tested by static thermal exposure at 1200 C and cyclic thermal exposure to 1000 C. The bond coats were based on Ni-Cr-Al alloys with additions of rare earth elements and Si. The ceramic coats were various ZrO2-Y2O3 compositions, of which the optimum was found to be ZrO2-8.9 wt percent Y2O3. Microstructural analysis showed that resistance to cracking during thermal exposure is strongly related to deleterious phase changes. Zones depleted of Al formed at the bond coat/ceramic coat interface due to oxidation and at the bond coat/substrate interface due to interdiffusion, leading eventually to breakdown of the bond coat. The 8.9 percent Y2O3 coating performed best because the as-sprayed metastable tetragonal phase converted slowly into the low-Y2O3 tetragonal plus high-Y2O3 cubic-phase mixture, so that the deleterious monoclinic phase was inhibited from forming. Failure appeared to start with the formation of circumferential cracks in the zirconia, probably due to compressive stresses during cooling, followed by the formation of radial cracks due to tensile stresses during heating. Cracks appeared to initiate at the Al2O3 scale/bond coat interface and propagate through the zirconia coating. Comparisons were made with the behavior of bulk ZrO2-Y2O3 and the relationship between the microstructure of the tetragonal phase and the phase diagram. A separate investigation was also made of the ZrO2-Al2O3 interface.

  2. Antibacterial coating on polymer for space application

    Energy Technology Data Exchange (ETDEWEB)

    Balagna, Cristina, E-mail: cristina.balagna@polito.it [Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Perero, Sergio; Ferraris, Sara; Miola, Marta [Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Fucale, Giacomo [Chemical, Clinical and Microbiological Analyses Department C.T.O., Via G. Zuretti 29, 10126 Torino (Italy); Manfredotti, Chiara; Battiato, Alfio [Physics Department, Centre of Excellence ' Nanostructured Interfaces and Surfaces' and CNISM, University of Torino, Via P. Giuria 1, 10125 Torino (Italy); Santella, Daniela [Thales Alenia Space - Italia, Space Infrastructures and Transportation, Engineering - Advanced Projects Unit, Strada Antica di Collegno 253, 10146 Torino (Italy); Verne, Enrica [Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Vittone, Ettore [Physics Department, Centre of Excellence ' Nanostructured Interfaces and Surfaces' and CNISM, University of Torino, Via P. Giuria 1, 10125 Torino (Italy); Ferraris, Monica [Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2012-08-15

    The microbiological contamination on board of spacecraft and orbital stations is a relevant problem in prolonged space exploration. For this purpose, an antibacterial silver nanocluster silica composite coating was deposited on a commercial polymer Combitherm{sup Registered-Sign }, suitable for aerospace application, using the radio frequency (RF) co-sputtering technique. The presence of metallic silver nanoclusters and silica was confirmed by energy dispersion spectrometry (EDS), x-ray photoelectron spectroscopy (XPS) and localized surface plasmon resonance (LSPR) detected through UV-visible absorption spectrophotometry (UV-Vis). The atomic force microscope (AFM) evidenced the coating morphology. The slight hydrophobicity of both coated and uncoated samples was revealed through the contact angle measurement. The antimicrobial behavior was verified through evaluation of the inhibition halo against several bacterial and fungal species. The coating enhanced the Combitherm{sup Registered-Sign} nano-hardness and its resistance to tensile and perforation tests; the coating wear resistance was measured by abrasion test against Kevlar. A folding procedure on the coated Combitherm{sup Registered-Sign} and storage in air for three months was also carried out without deterioration of the measured properties. The coating deposition did not influence the air permeability of Combitherm{sup Registered-Sign }. -- Highlights: Black-Right-Pointing-Pointer A silver nanocluster silica composite coating was deposited on a polymeric film. Black-Right-Pointing-Pointer A co-sputtering technique was used for the coating deposition. Black-Right-Pointing-Pointer The coating induced an antibacterial effect on the polymer film. Black-Right-Pointing-Pointer The coating improved the nano-hardness and the resistance to tensile and perforation.

  3. Effect of alginate/carboxyl methyl cellulose composite coating incorporated with clove essential oil on the quality of silver carp fillet and Escherichia coli O157:H7 inhibition during refrigerated storage.

    Science.gov (United States)

    Jalali, Nastaran; Ariiai, Peiman; Fattahi, Esmaeil

    2016-01-01

    The effects of alginate/carboxyl methylcellulose composite coating incorporated with clove essential oil on quality of silver carp fillet chilled storage (4 + 1 °C) were examined over a period of 16 days. The control samples (c), alginate/carboxyl methylcellulose coating (C-A), alginate/carboxyl methylcellulose composite coating incorporated with clove essential oil (with different concentration 1 and 1.5 %) (C-A + CEO1 % and C-A + CEO 15 % respectively) were analyzed by bacteriological (total viable counts (TVC) and total psychrotrophic counts (TPC)), biochemical (Peroxide value (PV), free fatty acid (FFA), total volatile base nitrogen (TVB-N), and pH) and sensory characteristics. Also, the efficacy of these treatments was investigated in control of the population of Eschershia coli O157:H7 inoculated in silver carp fillet. According to the obtained results, C-A + CEO 1.5 % showed lowest (p clove essential oil might be recommended as a preservative in the meat products. PMID:26787996

  4. Biofouling-resistant ceragenin-modified materials and structures for water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael; Altman, Susan J.; Jones, Howland D. T.; Savage, Paul B.

    2013-09-10

    This invention relates to methods for chemically grafting and attaching ceragenin molecules to polymer substrates; methods for synthesizing ceragenin-containing copolymers; methods for making ceragenin-modified water treatment membranes and spacers; and methods of treating contaminated water using ceragenin-modified treatment membranes and spacers. Ceragenins are synthetically produced antimicrobial peptide mimics that display broad-spectrum bactericidal activity. Alkene-functionalized ceragenins (e.g., acrylamide-functionalized ceragenins) can be attached to polyamide reverse osmosis membranes using amine-linking, amide-linking, UV-grafting, or silane-coating methods. In addition, silane-functionalized ceragenins can be directly attached to polymer surfaces that have free hydroxyls.

  5. Heat exchangers: Biofouling. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-04-01

    The bibliography contains citations concerning biological fouling and associated corrosion of heat exchangers and cooling systems. Topics include chlorination methods and systems, biocides, microbiological corrosion control, and alternative controls that comply with environmental regulations. Applications for cooling towers, ocean thermal energy conversion, nuclear power plants, and conventional oil- and coal-fired power plants are considered. Antifouling coatings for marine applications are discussed in separate bibliographies. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  6. Protein-resistant polymer coatings obtained by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Rusen, L. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH, Magurele, Bucharest (Romania); Mitu, B.; Filipescu, M.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Dinca, V., E-mail: dinali@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania)

    2013-08-01

    Adsorption of proteins and polysaccharides is known to facilitate microbial attachment and subsequent formation of biofilm on surfaces that ultimately results in its biofouling. Therefore, protein repellent modified surfaces are necessary to block the irreversible attachment of microorganisms. Within this context, the feasibility of using the Poly(ethylene glycol)-block-poly(ε-caprolactone) methyl ether (PEG-block-PCL Me) copolymer as potential protein-resistant coating was explored in this work. The films were deposited using Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique that allows good control of composition, thickness and homogeneity. The chemical and morphological characteristics of the films were examined using Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements and Atomic Force Microscopy (AFM). The FTIR data demonstrates that the functional groups in the MAPLE-deposited films remain intact, especially for fluences below 0.5 J cm{sup −2}. Optical Microscopy and AFM images show that the homogeneity and the roughness of the coatings are related to both laser parameters (fluence, number of pulses) and target composition. Protein adsorption tests were performed on the PEG-block-PCL Me copolymer coated glass and on bare glass surface as a control. The results show that the presence of copolymer as coating significantly reduces the adsorption of proteins.

  7. Electrocurtain coating process for coating solar mirrors

    Science.gov (United States)

    Kabagambe, Benjamin; Boyd, Donald W.; Buchanan, Michael J.; Kelly, Patrick; Kutilek, Luke A.; McCamy, James W.; McPheron, Douglas A.; Orosz, Gary R.; Limbacher, Raymond D.

    2013-10-15

    An electrically conductive protective coating or film is provided over the surface of a reflective coating of a solar mirror by flowing or directing a cation containing liquid and an anion containing liquid onto the conductive surface. The cation and the anion containing liquids are spaced from, and preferably out of contact with one another on the surface of the reflective coating as an electric current is moved through the anion containing liquid, the conductive surface between the liquids and the cation containing liquid to coat the conductive surface with the electrically conductive coating.

  8. Biofouling of granite-rapakivi in St. Petersburg monuments and in the quarry in Russia and Finland

    Science.gov (United States)

    Vlasov, Dmitry; Panova, Elena; Alampieva, Elena; Olhovaya, Elena; Popova, Tatyana; Vlasov, Alexey; Zelenskaya, Marina

    2013-04-01

    Granite-rapakivi was widely used in the architecture of St. Petersburg: the facades of buildings, embankments of rivers and canals, bridges, sculptural monuments, pedestals, facing the metro stations. This stone is rapidly destroyed due to the peculiarities of its structure. Biofouling of granite is insufficiently studied. Cause the destruction of granite can be bacteria, microscopic algae, fungi, mosses, lichens, higher plants, invertebrates and vertebrates. They often form specific lithobiotic communities that contribute to the destruction of granite-rapakivi. The objects of research were monuments of St. Petersburg (granite sculpture, facades, facing embankments) as well as granite-rapakivi quarries in Russia and Finland, where the stone was quarried for use in St. Petersburg. Sampling was carried out from the most typical biofouling sites. Different methods were applied for the study of damaged granite: petrographic analysis, light and scanning electron microscopy, methods for detection and identification of microorganisms, X-ray microprobe analysis. As result the main forms of granite destruction were described: fractures, ovoid weathering, granular disintegration, surface films, crusts and layers, pitting and fouling. Lichens, mosses, herbaceous and micromycetes were dominated on the granite-rapakivi in quarries. For example, in a Monferran quarry (Virolahti region) the complicated lithobiotic community was revealed. It included 30 species of micromycetes, 31 species of lichens, 10 species of moss. Bacteriological analysis showed the dominance of bacteria Bacillus, and actinomycetes in microbial biofilms. More than 100 species of plants were found on the granite embankments in St. Petersburg. They were confined to the cracks, seams of granite blocks. Plants and mosses were common to the granite embankments of rivers and canals in the central (historical) part of the city. Dimensions of mosses depend on the area of the deepening which they occupy. The most

  9. 复合型杀菌剂对生物粘泥处理效果的研究%Research on compound type biocides in biofouling control

    Institute of Scientific and Technical Information of China (English)

    夏璐; 刘芳; 薛松; 常新; 杨飞; 殷晓晨; 韩笑

    2011-01-01

    为了解决循环冷却水系统中生物粘泥大量滋生的问题,设计实验,考察了一定浓度的复合酶制剂与常规杀菌剂复配使用对生物粘泥的处理效果。研究结果表明,在酶制剂的辅助下,杀菌剂苯扎溴胺对生物粘泥的作用效果明显增加。180 mg/L是苯扎溴胺与酶复配的最佳浓度;酶与醋酸氯已定复配后对生物粘泥的杀菌效果有所增高,80 mg/L是醋酸氯已定与酶复配的最佳浓度。此外,与单一杀菌剂作用相比,加入酶会降解生物粘泥胞外聚合物,从而瓦解生物粘泥结构,使其内部的微生物暴露出来以便杀菌剂杀灭。%In order to resolve the problem of biofouling breeding in recirculating cooling water system,mixed antimicrobial characteristics of compound enzymes and certain biocides on biofouling were investigated.The results showed that the effect of compound bromogeramine on biofouling control increased obviously with the help of enzymes.Cooperated with compound enzymes,180 mg/L for bromogeramine and 80 mg/L for chlorhexidine acetate are the optimal concentrations to control biofilm.Compared with biocides alone,using enzymes to decompose EPS to wipe off the biofilm in circulating cooling water is an effective way for the reason that compound enzymes can break down biofouling structure,in order to make biofouling internal microbial exposed to biobicides.

  10. Innovative coatings and surface modification of titanium for sea water condenser applications

    International Nuclear Information System (INIS)

    Effectiveness of cooling water systems in various power plants to maintain highest electrical energy output per tonne of fuel is important as part of good energy management. Cooling water systems of nuclear power plants using seawater for cooling comes under constant attack from the marine and sea water environment. Many metallic components and civil structures in the cooling water systems like bridges, intake wells, intake pipes, pump house wells, water boxes, condenser pipes are subjected to severe fouling and corrosion which limits the service life and availability of power plants. The experience with a coastal water cooled power plant at Kalpakkam (MAPS), India, showed that chlorination and screening control macrofouling to a great extend by controlling protozoans, invertebrates, algae and fungi. However 90% of marine bacteria are resistant to such control measures, and they cause microfouling of condenser pipes leading to poor heat transfer and microbially influenced corrosion (MIC) failures. Titanium is used as condenser for Indian nuclear power plants employing sea water cooling, including the PFBR at Kalpakkam. Though titanium is excellent with respect to corrosion behavior under sea water conditions, its biocompatible nature results in biofouling and MIC during service. Therefore innovative antifouling coatings and surface modification techniques for titanium condenser applications in seawater and marine environments are the need of the hour. Extensive investigations were carried out by different methods including nanostructuring of surfaces for making them antibacterial. The microroughness of titanium was produced by repeated pickling and polishing which by itself reduced microbial adhesion. To utilize photocatalytic activity for antibacterial property, anodization of titanium surfaces followed by heat treatment was adopted and this also has controlled microbial fouling. Electroless plating of nanofilm of copper-nickel alloy decreased biofouling of

  11. Multi-layer coatings

    Energy Technology Data Exchange (ETDEWEB)

    Maghsoodi, Sina; Brophy, Brenor L.; Abrams, Ze' ev R.; Gonsalves, Peter R.

    2016-06-28

    Disclosed herein are coating materials and methods for applying a top-layer coating that is durable, abrasion resistant, highly transparent, hydrophobic, low-friction, moisture-sealing, anti-soiling, and self-cleaning to an existing conventional high temperature anti-reflective coating. The top coat imparts superior durability performance and new properties to the under-laying conventional high temperature anti-reflective coating without reducing the anti-reflectiveness of the coating. Methods and data for optimizing the relative thickness of the under-layer high temperature anti-reflective coating and the top-layer thickness for optimizing optical performance are also disclosed.

  12. COMPARISON OF SOL-GEL SILICATE COATINGS ON Ti SUBSTRATE

    Directory of Open Access Journals (Sweden)

    DIANA HORKAVCOVÁ

    2012-12-01

    Full Text Available The objective of the submitted work was to prepare and to characterize two types of silicate coatings prepared by the sol-gel method using the dip-coating technique on a titanium substrate. Efforts have been made to use mechanical properties of bio-inert titanium and bioactive properties of a silicate layer enriched with an admixture of compounds identified below. The first group consisted of silicate coatings containing silver, brushite and monetite. The other group of silicate coatings contained calcium nitrate and triethyl phosphate. Mechanically and chemically treated titanium substrates were dipped into sols and dried and fired. Silicate coatings from the first group were also chemically treated in 10 mol.l-1 solution of sodium hydroxide. All coatings were measured to determine their adhesive and bioactive properties and furthermore the antibacterial properties were tested in the case of first group. Surfaces of the coated substrates were investigated after the firing and after the individual tests with optical and electron microscopy and X-ray microdiffraction. A tape test demonstrated excellent adhesive property of all coatings to the substrate, classified with degree 5. A static in vitro test demonstrated bioactivity of nearly all the coatings. The basic silicate coating from the first group and one type of coating from the second group were identified as inert. Antibacterial properties of silicate coatings containing silver showed to be different when tested against Escherichia coli bacteria. A complete inhibition of the growth of bacteria under our experimental conditions was observed for the coating containing silver and monetite and a partial inhibition of the growth of bacteria for coatings containing silver and silver in combination with brushite.

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

    Science.gov (United States)

    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

  14. Biofouling-Resistant Impedimetric Sensor for Array High-Resolution Extracellular Potassium Monitoring in the Brain

    Directory of Open Access Journals (Sweden)

    Ruben Machado

    2016-10-01

    Full Text Available Extracellular potassium concentration, [K+]o, plays a fundamental role in the physiological functions of the brain. Studies investigating changes in [K+]o have predominantly relied upon glass capillary electrodes with K+-sensitive solution gradients for their measurements. However, such electrodes are unsuitable for taking spatio-temporal measurements and are limited by the surface area of their tips. We illustrate seizures invoked chemically and in optogenetically modified mice using blue light exposure while impedimetrically measuring the response. A sharp decrease of 1–2 mM in [K+]o before each spike has shown new physiological events not witnessed previously when measuring extracellular potassium concentrations during seizures in mice. We propose a novel approach that uses multichannel monolayer coated gold microelectrodes for in vivo spatio-temporal measurements of [K+]o in a mouse brain as an improvement to the conventional glass capillary electrode.

  15. Efficiency of surface modified Ti coated with copper nanoparticles to control marine bacterial adhesion under laboratory simulated conditions

    Indian Academy of Sciences (India)

    CHOKKALINGAM PRIYA; GANESSIN ARAVIND; WILSON RICHARD THILAGARAJ

    2016-04-01

    Titanium (Ti) used as condenser material in nuclear power plants encounter severe biofouling in marine environment which in turn affects the efficiency of the metal. To reduce the biofouling by marine microorganisms, surface modification of the Ti was carried out by anodization process to obtain nanotubes (TiO$_2$-NTs). The electrolyte solution containing 1% of ammonium fluoride resulted in uniform growth of TiO$_2$-NTs. TiO$_2$-NTs were furthercoated with chemically synthesized copper nanoparticles (NT-CuNP) using 3-amino propyl triethoxy silane as a coupling agent. NT-CuNP was characterized by field-emission scanning electron microscopy (FE-SEM), energydispersivespectroscopy and X-ray diffraction. The stability of the coating was determined by the amount of Cu$^+$ ions released into the surrounding using AAS. The microbial adhesion on the surface of Ti, TiO$_2$-NTs and NT-CuNPcoupons were evaluated by sea water exposure studies using total viable count method and also characterized by FE-SEM for any morphological changes. The NT-CuNP coupons show a 60% reduction in microbial adhesion whencompared to control Ti coupons.

  16. Flow coating apparatus and method of coating

    Science.gov (United States)

    Hanumanthu, Ramasubrahmaniam; Neyman, Patrick; MacDonald, Niles; Brophy, Brenor; Kopczynski, Kevin; Nair, Wood

    2014-03-11

    Disclosed is a flow coating apparatus, comprising a slot that can dispense a coating material in an approximately uniform manner along a distribution blade that increases uniformity by means of surface tension and transfers the uniform flow of coating material onto an inclined substrate such as for example glass, solar panels, windows or part of an electronic display. Also disclosed is a method of flow coating a substrate using the apparatus such that the substrate is positioned correctly relative to the distribution blade, a pre-wetting step is completed where both the blade and substrate are completed wetted with a pre-wet solution prior to dispensing of the coating material onto the distribution blade from the slot and hence onto the substrate. Thereafter the substrate is removed from the distribution blade and allowed to dry, thereby forming a coating.

  17. Biofouling and pollutant removal during long-term operation of an anaerobic membrane bioreactor treating municipal wastewater.

    Science.gov (United States)

    Herrera-Robledo, M; Morgan-Sagastume, J M; Noyola, A

    2010-01-01

    Two different sludge retention times (SRTs) were tested in order to assess the impact on membrane fouling and effluent quality in an anaerobic membrane bioreactor (AnMBR). Two up-flow anaerobic sludge bed (UASB) reactors (1 l volume) coupled to external tubular ultrafiltration membranes (filtration area = 81 cm(2)) were operated at a hydraulic retention time of 3 h and two different SRTs (100 and 60 days). The transmembrane pressure (TMP), flux (J) and relevant parameters to assess water quality were measured. Effluents from UASB reactors were filtered for 500 h without intermediate cleaning. The permeate met Mexican standards for wastewater reclamation in both tested conditions. Abrupt and periodical changes in the TMP and J were noticed during the experimental period. A fouling layer collapse and compression hypothesis was set forth in order to explain these changes. An autopsy performed on biofouled membranes indicated that deposited mass was mainly composed of volatile solids (85%) and the rest related to mineral matter, with the presence of inorganic salts containing Ca, Mg, Fe, P and Si. Biomass in the fouling layer was estimated at 0.27% based on the DNA/biomass ratio for the bacterial biofilm. No clear difference in membrane fouling was detected under the two SRTs applied to the systems. However, when operated over 500 h, repetitive sudden TMP and flux changes occurred later in system A (SRT of 100 days) than in system B (SRT of 60 days) suggesting a stronger fouling layer structure in the former. PMID:20390553

  18. Biofouling growth in cold estuarine waters and evaluation of some chitosan and copper anti-fouling paints.

    Science.gov (United States)

    Pelletier, Emilien; Bonnet, Claudie; Lemarchand, Karine

    2009-06-01

    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

  19. Biofouling resistance of boron-doped diamond neural stimulation electrodes is superior to titanium nitride electrodes in vivo

    Science.gov (United States)

    Meijs, S.; Alcaide, M.; Sørensen, C.; McDonald, M.; Sørensen, S.; Rechendorff, K.; Gerhardt, A.; Nesladek, M.; Rijkhoff, N. J. M.; Pennisi, C. P.

    2016-10-01

    Objective. The goal of this study was to assess the electrochemical properties of boron-doped diamond (BDD) electrodes in relation to conventional titanium nitride (TiN) electrodes through in vitro and in vivo measurements. Approach. Electrochemical impedance spectroscopy, cyclic voltammetry and voltage transient (VT) measurements were performed in vitro after immersion in a 5% albumin solution and in vivo after subcutaneous implantation in rats for 6 weeks. Main results. In contrast to the TiN electrodes, the capacitance of the BDD electrodes was not significantly reduced in albumin solution. Furthermore, BDD electrodes displayed a decrease in the VTs and an increase in the pulsing capacitances immediately upon implantation, which remained stable throughout the whole implantation period, whereas the opposite was the case for the TiN electrodes. Significance. These results reveal that BDD electrodes possess a superior biofouling resistance, which provides significantly stable electrochemical properties both in protein solution as well as in vivo compared to TiN electrodes.

  20. Biofouling Growth in Cold Estuarine Waters and Evaluation of Some Chitosan and Copper Anti-Fouling Paints

    Directory of Open Access Journals (Sweden)

    Karine Lemarchand

    2009-07-01

    Full Text Available 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.

  1. Factors influencing the en route survivorship and post-voyage growth of a common ship biofouling organism, Bugula neritina.

    Science.gov (United States)

    Schimanski, Kate B; Piola, Richard F; Goldstien, Sharyn J; Floerl, Oliver; Grandison, Clare; Atalah, Javier; Hopkins, Grant A

    2016-09-01

    The likelihood that viable non-indigenous biofouling species will survive a voyage on a vessel is influenced by a range of factors, including the speed, duration, and route of the voyage and the amount of time the vessel spends in port. In this study, a land-based dynamic flow device was used to test the effect of recruit age, vessel speed and voyage duration on the survivorship and growth of the bryozoan Bugula neritina. In the experiment, one-week-old recruits had a higher likelihood (100%) of surviving voyages than older (one-month-old, 90%) or younger (one-day-old, 79%) recruits, but survival was not influenced by vessel speed (6 and 18 knots) or voyage duration (two and eight days). The results suggest that the non-indigenous species B. neritina can be effectively transferred at a range of ages but one-week-old recruits are more likely to survive the translocation process and survive in the recipient environment.

  2. Dynamics of biofilm formation under different nutrient levels and the effect on biofouling of a reverse osmosis membrane system.

    Science.gov (United States)

    Chen, Xi; Suwarno, Stanislaus Raditya; Chong, Tzyy Haur; McDougald, Diane; Kjelleberg, Staffan; Cohen, Yehuda; Fane, Anthony G; Rice, Scott A

    2013-01-01

    Pseudomonas aeruginosa PAO1 wild type and a mucoid derivative (FRD1) which over produces alginate were used to foul reverse osmosis (RO) membranes. When operated at a constant flux, biofilm formation on the RO membrane resulted in a slow rise in transmembrane pressure (TMP) of 22% for the initial four days of operation, followed by a sharp increase of 159% over the following two days. The initial slow increase in TMP was probably due to the formation of a biofilm on the membrane surface, which then accelerated the rate of biofouling through the effect of concentration polarization. At later stages of operation, most of the bacterial biomass consisted of dead cells. The amount of extracellular polymeric substances appeared to correlate positively with the number of dead cells. The results indicate that prolonging the initial stage of slow TMP increase and avoiding the latter stage of accelerated TMP increase would provide a sustainable operation of the RO system. These results suggest that nutrient limitation could reduce biofilm accumulation and delay the increase in TMP.

  3. Effect of conventional chemical treatment on the microbial population in a biofouling layer of reverse osmosis systems.

    Science.gov (United States)

    Bereschenko, L A; Prummel, H; Euverink, G J W; Stams, A J M; van Loosdrecht, M C M

    2011-01-01

    The impact of conventional chemical treatment on initiation and spatiotemporal development of biofilms on reverse osmosis (RO) membranes was investigated in situ using flow cells placed in parallel with the RO system of a full-scale water treatment plant. The flow cells got the same feed (extensively pre-treated fresh surface water) and operational conditions (temperature, pressure and membrane flux) as the full-scale installation. With regular intervals both the full-scale RO membrane modules and the flow cells were cleaned using conventional chemical treatment. For comparison some flow cells were not cleaned. Sampling was done at different time periods of flow cell operation (i.e., 1, 5, 10 and 17 days and 1, 3, 6 and 12 months). The combination of molecular (FISH, DGGE, clone libraries and sequencing) and microscopic (field emission scanning electron, epifluorescence and confocal laser scanning microscopy) techniques made it possible to thoroughly analyze the abundance, composition and 3D architecture of the emerged microbial layers. The results suggest that chemical treatment facilitates initiation and subsequent maturation of biofilm structures on the RO membrane and feed-side spacer surfaces. Biofouling control might be possible only if the cleaning procedures are adapted to effectively remove the (dead) biomass from the RO modules after chemical treatment.

  4. Marine bio-fouling of different alloys exposed to continuous flowing fresh seawater by electrochemical impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    Khalid Al-Muhanna

    2016-07-01

    Full Text Available The petroleum industry and desalination plants suffer from marine bio-fouling problems that have a major role in the stimulation of the corrosion process. Thus, the aim of this study was to investigate the effect of the micro and the macro-organisms, on the corrosion behavior of different alloys used in Kuwait’s industries. The alloys used in this study were; sanicro 28, stainless steel 316L, Cu–Ni 70–30, and titanium. The electrochemical impedance spectroscopy was used in this study in order to determine the corrosion susceptibility of different alloys exposed to continuous fresh seawater. This was achieved by calculating the charge transfer resistance of the metal surface and the resistance of the solution. The total exposure time of the tests was about 180 days. The visual inspection of the tested samples, showed a bio-film formation on the surface of these samples. Also, it was observed that the stainless steel 316, sanicro 28, Cu–Ni 70–30, and titanium alloys exhibited good corrosion resistance.

  5. Fabrication of Duplex Coated U-Mo-Ti Atomized Powder

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ji Min; Kim, Woo Jeong; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ryu, Ho Jin [Korea Advanced Institue of Science and Technology, Daejeon (Korea, Republic of)

    2013-10-15

    The results of an annealing test showed that the coating layers inhibit the formation of interaction layers. The results of duplex coating showed that nitride coating layers inhibit the formation of other coating layers. High-density U-Mo alloys are regarded as promising candidates for advanced research reactor fuel as they have shown stable irradiation performance when compared to other uranium alloys and compounds. However, interaction layer formation between the U-Mo alloys and Al matrix degrades the irradiation performance of U-Mo dispersion fuel. Therefore, the addition of Ti in U-Mo alloys, the addition of Si in a Al matrix, and silicide or nitride coating on the surface of U-Mo particles have been proposed to inhibit the interaction layer growth. In this study, U-Mo-Ti alloy powder was produced using a centrifugal atomization method. In addition, nitride and silicide duplex coating layers were fabricated on the surface of the U-Mo-Ti particles. The coated powders were characterized by using X-ray diffraction, SEM, and EDX. Silicide and nitride single coating layers were fabricated on the surface of U-7wt%Mo-1wt%Ti alloys with a thickness of about 10.20 micrometers.

  6. Coating of pumps; coating af pumper

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Hans; Moritzen, J.; Thoegersen, Jeanette

    2005-11-15

    Coating of pumps is a quite new activity. For many years pipes and containers have been coated inside in order to avoid corrosion, but the technology has only been used inside pumps for the last ten years. The technology comes from USA and is originally developed in the space technology industry as an exceptionally durable and corrosion constant coating. The project is a further development of results found in a previous R and D project in which measurements were performed before and after coating two different installations. Both installations showed large efficiency improvements. This project supplements the theory behind losses in pumps with measurements on more pumps. (BA)

  7. Evaluation of Antimicrobial Properties of Edible Surface Coating Based on Carrageenan Conjugated with Silver Nanoparticles on Sekaki Papaya (Carica Papaya cv. Sekaki): A New Antimicrobial Edible Coating

    International Nuclear Information System (INIS)

    Antibacterial properties of edible surface coating based on carrageenan incorporated with silver nanoparticles (SNPs), was investigated against Escherichia coli and Staphylococcus aureus to obtain optimum concentration of SNPs. Results obtained indicate that SNPs with concentration of 40 ml L-1 effectively inhibited the growth of both Gram negative and Gram positive bacteria. Sekaki papaya fruits were then coated with prepared edible coating formulation comprising of carrageenan (0.8 % w/v) and glycerol (1.0 % w/v) with and without SNPs (40 ppm) and stored at ambient conditions (26±2 degree Celsius and 60±10 % RH). Microbial analysis of coated and uncoated papaya samples during storage indicated that the edible coating comprising of carrageenan, glycerol and SNPs, strongly inhibited the growth of fungus that caused post harvest diseases of papaya as compared to uncoated and coated papaya fruits with edible coating without SNPs. (author)

  8. Alkali Silicate Glass Coatings for Mitigating the Risks of Tin Whiskers

    Science.gov (United States)

    Hillman, Dave; Wilcoxon, Ross; Lower, Nate; Grossman, Dan

    2015-12-01

    Alkali silicate glass (ASG) coatings were investigated as a possible method for inhibiting tin whisker initiation and growth. The aqueous-based ASG formulations used in this study were deposited with equipment and conditions that are typical of those used to apply conventional conformal coatings. Processes for controlling ASG coating properties were developed, and a number of ASG-based coating combinations were applied to test components with pure tin surfaces. Coatings were applied both in a laboratory environment at Rockwell Collins and in a manufacturing environment at Plasma Ruggedized Solutions. Testing in elevated humidity/temperature environments and subsequent inspection of the test articles identified coating combinations that inhibited tin whisker growth as well as other material combinations that actually accelerated tin whisker growth. None of the coatings evaluated in this study, including conventional acrylic and Parylene conformal coatings, completely prevented the formation of tin whiskers. Two of the coatings were particularly effective at reducing the risks of whisker growth, albeit through different mechanisms. Parylene conformal coating almost, but not completely, eliminated whisker formation, and only a few tin whiskers were found on these surfaces during the study. A composite of ASG and alumina nanoparticles inhibited whisker formation to a lesser degree than Parylene, but did disrupt whisker growth mechanisms so as to inhibit the formation of long, and more dangerous, tin whiskers. Additional testing also demonstrated that the conformal coatings had relatively little effect on the dielectric loss of a stripline test structure operating at frequencies over 30 GHz.

  9. 污水深度回用反渗透膜面微生物污染机理试验研究%Experimental Investigation of Biofouling Mechanism of RO Membrane for Wastewater Advanced Reuse

    Institute of Scientific and Technical Information of China (English)

    于海琴; 孙慧德; 陈蕊; 杨成永; 周煜坤

    2013-01-01

    微生物污染是最复杂的膜污染形式,是污水深度回用反渗透设备运行过程关注的焦点.通过实验室静态试验和错流过滤动态试验研究了污水回用反渗透膜的微生物污染的机理和特性,结果表明:造成污染的微生物主要为杆菌和丝状菌;在没有微生物源及没有微生物生长和繁殖的必需营养物质的情况下,膜面基本不发生微生物污染;杀菌处理对于防止微生物污染很重要,已经污染的膜面更易于发生微生物污染,做好反渗透设备的停备用保护工作是防止微生物污染的必要手段.%Biofouling has become the focus of RO in water and wastewater treatment. Experimental investigation of RO biofouling mechanism and characteristics in wastewater advanced reuse was carried out by static test and cross-flow dynamic test on a lab-scale membrane fouling simulator ( MFS). The experimental results show that the major contributors to biofouling are coli and filamentous bacteria; there ' usually is no biofouling on the RO membrane surface with the absence of microbial source and nutrient composition; it is easy to cause biofouling on the fouled membrane; the germicidal treatment and the protection in the shut-down period are important for RO. Guidance for the analysis and reduction of biofouling in the practical engineering is provided.

  10. Heat and Mass Transfer Model of Biofouling Formation%微牛物污垢形成的传热传质模型

    Institute of Scientific and Technical Information of China (English)

    曹生现; 孙嘉伟; 刘洋; 张艳辉; 杨善让; 徐志明

    2012-01-01

    为研究循环冷却水中微生物污垢的形成,本文综合考虑微生物的传质和吸附过程,建立了微生物污垢形成的传热传质模型。该模型基于微生物生长动力学原理,建立了水质参数与污垢热阻的关联关系,并考虑了微生物比生长速率、致垢物质的沉积与脱除速率。通过微生物污垢动态模拟实验,对相关参数进行分析测量,以验证该传热传质模型准确性。实验结果表明:由该模型计算的污垢热阻预测值能够与实验结果很好吻合,验证了该模型的正确性,其综合预测误差为5.8%。%For studying biofouling formation in circulating cooling water, the heat and mass transfer model of biofouling formation is established in this paper. This model considers microbial mass transfer and adsorption process. This model, based on microbial growth dynamics theory, can reflect the association between fouling resistance and water quality parameters. This model also considers the microbial specific growth rate, the deposition and removal rates of fouling material. This model has been verified through the relevant parameters obtained in biofouling dynamic simulation experiments. The fouling predictive value calculated by this model can fit with the experimental results well, the error of composite prediction is 5.8%.

  11. Reduction of the inflammatory responses against alginate-poly-L-lysine microcapsules by anti-biofouling surfaces of PEG-b-PLL diblock copolymers.

    Directory of Open Access Journals (Sweden)

    Milica Spasojevic

    Full Text Available Large-scale application of alginate-poly-L-lysine (alginate-PLL capsules used for microencapsulation of living cells is hampered by varying degrees of success, caused by tissue responses against the capsules in the host. A major cause is proinflammatory PLL which is applied at the surface to provide semipermeable properties and immunoprotection. In this study, we investigated whether application of poly(ethylene glycol-block-poly(L-lysine hydrochloride diblock copolymers (PEG-b-PLL can reduce the responses against PLL on alginate-matrices. The application of PEG-b-PLL was studied in two manners: (i as a substitute for PLL or (ii as an anti-biofouling layer on top of a proinflammatory, but immunoprotective, semipermeable alginate-PLL100 membrane. Transmission FTIR was applied to monitor the binding of PEG-b-PLL. When applied as a substitute for PLL, strong host responses in mice were observed. These responses were caused by insufficient binding of the PLL block of the diblock copolymers confirmed by FTIR. When PEG-b-PLL was applied as an anti-biofouling layer on top of PLL100 the responses in mice were severely reduced. Building an effective anti-biofouling layer required 50 hours as confirmed by FTIR, immunocytochemistry and XPS. Our study provides new insight in the binding requirements of polyamino acids necessary to provide an immunoprotective membrane. Furthermore, we present a relatively simple method to mask proinflammatory components on the surface of microcapsules to reduce host responses. Finally, but most importantly, our study illustrates the importance of combining physicochemical and biological methods to understand the complex interactions at the capsules' surface that determine the success or failure of microcapsules applicable for cell-encapsulation.

  12. PIT Coating Requirements Analysis

    International Nuclear Information System (INIS)

    This study identifies the applicable requirements for procurement and installation of a coating intended for tank farm valve and pump pit interior surfaces. These requirements are intended to be incorporated into project specification documents and design media. This study also evaluates previously recommended coatings and identifies requirement-compliant coating products

  13. PIT Coating Requirements Analysis

    Energy Technology Data Exchange (ETDEWEB)

    MINTEER, D.J.

    2000-10-20

    This study identifies the applicable requirements for procurement and installation of a coating intended for tank farm valve and pump pit interior surfaces. These requirements are intended to be incorporated into project specification documents and design media. This study also evaluates previously recommended coatings and identifies requirement-compliant coating products.

  14. Optical Properties of Window Coatings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Window coating used for the building in recent years is described. Important design principles, practical coating materials, and attainable optical properties for research-type coatings are introduced. Discussion is carried out on the spectrally selective coatings, the electrochromic coatings, and the thermochromic coatings.

  15. Metallic coating of microspheres

    International Nuclear Information System (INIS)

    Extremely smooth, uniform metal coatings of micrometer thicknesses on microscopic glass spheres (microspheres) are often needed as targets for inertial confinement fusion (ICF) experiments. The first part of this paper reviews those methods used successfully to provide metal coated microspheres for ICF targets, including magnetron sputtering, electro- and electroless plating, and chemical vapor pyrolysis. The second part of this paper discusses some of the critical aspects of magnetron sputter coating of microspheres, including substrate requirements, the sticking of microspheres during coating (preventing a uniform coating), and the difficulties in growing the desired dense, smooth, uniform microstructure on continuously moving spherical substrates

  16. ATHENA optimized coating design

    DEFF Research Database (Denmark)

    Ferreira, Desiree Della Monica; Christensen, Finn Erland; Jakobsen, Anders Clemen;

    2012-01-01

    The optimization of coating design for the ATHENA mission si described and the possibility of increasing the telescope effective area in the range between 0.1 and 10 keV is investigated. An independent computation of the on-axis effective area based on the mirror design of ATHENA is performed...... in order to review the current coating baseline. The performance of several material combinations, considering a simple bi-layer, simple multilayer and linear graded multilayer coatings are tested and simulation of the mirror performance considering both the optimized coating design and the coating...

  17. Antibacterial polymer coatings.

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Mollye C.; Allen, Ashley N.; Barnhart, Meghan; Tucker, Mark David; Hibbs, Michael R.

    2009-09-01

    A series of poly(sulfone)s with quaternary ammonium groups and another series with aldehyde groups are synthesized and tested for biocidal activity against vegetative bacteria and spores, respectively. The polymers are sprayed onto substrates as coatings which are then exposed to aqueous suspensions of organisms. The coatings are inherently biocidal and do not release any agents into the environment. The coatings adhere well to both glass and CARC-coated coupons and they exhibit significant biotoxicity. The most effective quaternary ammonium polymers kills 99.9% of both gram negative and gram positive bacteria and the best aldehyde coating kills 81% of the spores on its surface.

  18. Ion sequestration particles for naval anticorrosion coatings

    Science.gov (United States)

    Zguris, Zachary Z.

    Corrosion is the electrochemical process of a metal returning to its lower energy state, the metal oxide. The cost of corrosion is difficult to estimate. One area particularly susceptible to corrosion problems with high maintenance costs is that of the 20,000 tanks existent in the US Naval Fleet. The Navy is sponsoring the development of novel coatings and additives that can be used to decrease the rising corrosion related costs. This dissertation describes in detail the synthesis of Ion Sequestration Particles (ISP) that when added to the standard MIL-DTL-24441 or potentially another coating system act to enhance the anticorrosion properties of the coating. A solid ion sequestration core material (SISCM) is first produced. The core is then encapsulated in a second stage forming a shell that protects the SISCM sufficiently from the harmful interactions with uncured epoxy based coatings. ISPs were designed to sequester harmful ions while releasing passivating ions in their place. The passivating ions then migrate to defect sites at the coating interface where they act to inhibit corrosion. The anticorrosion performance of ISPs in epoxy coatings has been demonstrated by both 500 hrs of hot deionized water immersion and 1000 hrs of salt spray exposure (ASTM B117). The best improvements in coating performance are attained with ISP content ranging from 5-10 wt % loading in a coating. ISPs were designed to limit the transport of harmful ions through the coating. However this work has determined high diffusion coefficients for ions (CI- and PO42-) through the epoxy matrix. Without ISPs, the diffusion coefficient through the MIL-DTL-24441 coating was determined for phosphate to be 1.16x10-7 cm2/s and for chloride to be in the range of 2.7x10-9 to 5.6x10-10 cm2/s. The addition of 5 wt % ISPs to the coating had the effect of decreasing the diffusion coefficient by an average of 25.5%. These results yield the conclusion that the enhanced anticorrosion properties of coatings

  19. Coated Aerogel Beads

    Science.gov (United States)

    Littman, Howard (Inventor); Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor)

    2014-01-01

    Methods and apparatus for coating particulate material are provided. The apparatus includes a vessel having a top and a bottom, a vertically extending conduit having an inlet in the vessel and an outlet outside of the vessel, a first fluid inlet in the bottom of the vessel for introducing a transfer fluid, a second fluid inlet in the bottom of the vessel for introducing a coating fluid, and a fluid outlet from the vessel. The method includes steps of agitating a material, contacting the material with a coating material, and drying the coating material to produce a coated material. The invention may be adapted to coat aerogel beads, among other materials. A coated aerogel bead and an aerogel-based insulation material are also disclosed.

  20. Effects of solar PAR and UV radiation on tropical biofouling communities

    KAUST Repository

    Dobretsov, SV

    2010-03-08

    We investigated the effect of solar ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) on the development of tropical micro- and macrofouling communities for 30 d. The experimental design involved 3 treatments: full spectrum (PAR+UVR), PAR only, and minimal light (reduced PAR and UVR). Terminal restriction fragment length polymorphism analysis demonstrated that different light conditions resulted in the formation of highly different microbial communities. The lowest densities of bacteria were found under the full spectrum treatment, while the lowest densities of diatoms were found in the minimal light treatment. Macrofouling communities consisted of 13 species and differed among light treatments. In the presence of UVR, communities had low species diversity, evenness, and richness, while in minimal light and PAR treatments, communities had high species diversity, evenness, and richness. Similarity percentage (SIMPER) analysis revealed that the tubeworm Hydroides elegans, the alga Ulva (Enteromorpha) sp., and the bivalve Perna viridis were the species responsible for most of the dissimilarities in macrofouling communities among treatments. While densities of H. elegans were similar in the PAR and minimal light treatments, this polychaete had higher growth rates under minimal light conditions. We conclude that UVR and PAR directly control the development of shallow micro- and macrofouling communities by inhibiting the recruitment and growth of sensitive species and promoting the growth of resistant species, but also that these forms of solar radiation influence the surface cues available to competent larvae by altering the development of the microbial community.

  1. Combustion chemical vapor desposited coatings for thermal barrier coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States)

    1995-10-01

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings.

  2. Heritage materials and biofouling mitigation through UV-C irradiation in show caves: state-of-the-art practices and future challenges.

    Science.gov (United States)

    Borderie, Fabien; Alaoui-Sossé, Badr; Aleya, Lotfi

    2015-03-01

    Biofouling, i.e., colonization of a given substrate by living organisms, has frequently been reported for heritage materials and particularly on stone surfaces such as building facades, historical monuments, and artworks. This also concerns subterranean environments such as show caves, in which the installation of artificial light for tourism has led to the proliferation of phototrophic microorganisms. In Europe nowadays, the use of chemicals in these very sensitive environments is scrutinized and regulated by the European Union. New and environmentally friendly processes must be developed as alternative methods for cave conservation. For several years, the UV irradiation currently used in medical facilities and for the treatment of drinking water has been studied as a new innovative method for the conservation of heritage materials. This paper first presents a review of the biofouling phenomena on stone materials such as building facades and historical monuments. The biological disturbances induced by tourist activity in show caves are then examined, with special attention given to the methods and means to combat them. Thirdly, a general overview is given of the effects of UV-C on living organisms, and especially on photosynthetic microorganisms, through different contexts and studies. Finally, the authors' own experiments and findings are presented concerning the study and use of UV-C irradiation to combat algal proliferation in show caves. Both laboratory and in situ results are summarized and synthesized from their previously published works. The application of UV in caves is discussed and further experiments are proposed to enhance research in this domain.

  3. 滨海电厂循环水系统海生物污染防治%Marine Biofouling Control in Circulating Water System of Coastal Power Plant

    Institute of Scientific and Technical Information of China (English)

    宋伟伟; 贾思洋; 周晓光; 张林

    2013-01-01

    The characteristic, damage and control methods of marine biofouling in circulating water system of coastal power plant were introduced in this paper, and the application of biocide was emphasized. Adopting alternatively non-oxidative biocide and oxidative biocide was an effective solution to marine biofouling, and the method of electrolyzing seawater antifouling technique was economic to large-scale circulating water system.%  要:本文介绍了滨海电厂循环水系统的海生物污染及危害,总结了滨海电厂循环水系统海生物污染的防治方法,并重点介绍了应用较广泛的杀生剂处理方法。非氧化性杀生剂与氧化性杀生剂交替使用是一种有效的防治海生物污染的方案,电解海水制氯防污技术对于大型循环水处理系统是经济合适的方案。

  4. 金黄色葡萄球菌超抗原样蛋白-5抑制人脐血源性内皮祖细胞黏附功能及其机制研究%Staphylococcal superantigen-like protein-5 inhibits adhesion of human umbilical cord blood-derived endothelial progenitor cells to P-selectin-coated surface

    Institute of Scientific and Technical Information of China (English)

    梁华; 曲小龙; 胡厚源; 宋治远; 程彦; 张静

    2011-01-01

    目的 研究金黄色葡萄球菌超抗原样蛋白-5 (staphylococcal superantigen-like protein-5,SSL5)与人脐血源性内皮祖细胞(endothelial progenitor cells,EPCs)表面P-选择素糖蛋白配体-1 (P-selectin glycoprotein ligand-1,PSGL-1) 的结合情况,及其对内皮祖细胞黏附功能的影响.方法 从金黄色葡萄球菌 NCTC 8325菌株的基因组中,扩增ssl5基因,并进行重组SSL5蛋白表达载体的构建.采用密度梯度离心法分离得到脐血中的单个核细胞并进行体外培养,对贴壁细胞在激光共聚焦显微镜下观察其摄取乙酰化低密度脂蛋白(DiI-acLDL)和结合荆豆凝集素(FITC-UEA-1)的情况.以流式细胞仪分析SSL5与EPCs表面PSGL-1的结合情况;以calcein-AM负载EPCs后,定量分析SSL5对EPCs在P-选择素包被表面黏附的抑制作用.结果 DiI-acLDL/ FITC-UEA-1双染阳性的细胞为EPCs.PSGL-1在EPCs表面有较丰富的表达,阳性细胞率为76.6%.SSL5与EPCs的结合随着SSL5浓度的增加而显著升高;并且,SSL5可竞争性抑制抗PSGL-1单克隆抗体(KPL-1)与EPCs的结合.SSL5可显著抑制EPCs在P-选择素表面的黏附,终浓度为30 mg/L的SSL5对EPCs在P-选择素表面黏附的抑制率已接近10 mg/L的KPL-1的效应,两者与空白对照组比较,差异有统计学意义(P<0.01).结论 SSL5可与EPCs表面的PSGL-1结合,而抑制EPCs在P-选择素表面的黏附,提示SSL5可能通过抑制EPCs与损伤内皮或激活的血小板之间的黏附,进而抑制EPCs对损伤内皮的修复作用.%Objective To investigate the binding of staphylococcal superantigen-like protein-5 (SSL5) to P-selectin glycoprotein ligand-1 (PSGL-1) on human umbilical cord blood-derived endothelial progenitor cells (EPCs) and the inhibitive effect of SSL5 on the adhesion of EPCs to P-selectin-coated surface.Methods SSL5 gene was amplified from the genome of Staphylococcus aureus NCTC 8325 and cloned into a vector for expressing recombinant SSL5 protein. Mononuclear cells were

  5. Preliminary coating design and coating developments for ATHENA

    DEFF Research Database (Denmark)

    Jakobsen, Anders Clemen; Ferreira, Desiree Della Monica; Christensen, Finn Erland;

    2011-01-01

    We present initial novel coating design for ATHENA. We make use of both simple bilayer coatings of Ir and B4C and more complex constant period multilayer coatings to enhance the effective area and cover the energy range from 0.1 to 10 keV. We also present the coating technology used for these...... designs and present test results from coatings....

  6. Polyurethane Organosilicate Nanocomposites as Blood Compatible Coatings

    Directory of Open Access Journals (Sweden)

    Johnson H. Y. Chung

    2012-02-01

    Full Text Available Polymer clay nanocomposites (NCs show remarkable potential in the field of drug delivery due to their enhanced barrier properties. It is hypothesised that well dispersed clay particles within the polymer matrix create a tortuous pathway for diffusing therapeutic molecules, thereby resulting in more sustained release of the drug. As coatings for medical devices, these materials can simultaneously modulate drug release and improve the mechanical performance of an existing polymer system without introducing additional materials with new chemistries that can lead to regulatory concerns. In this study, polyurethane organosilicate nanocomposites (PUNCs coated onto stainless steel wires were evaluated for their feasibility as blood compatible coatings and as drug delivery systems. Heparin was selected as the model drug to examine the impact of silicate loading and modifier chain length in modulating release. Findings revealed that better dispersion was achieved from samples with lower clay loadings and longer alkyl chains. The blood compatibility of PUNCs as assessed by thrombin generation assays showed that the addition of silicate particles did not significantly decrease the thrombin generation lag time (TGT, p = 0.659 or the peak thrombin (p = 0.999 of polyurethane (PU. PUNC coatings fabricated in this research were not cytotoxic as examined by the cell growth inhibition assay and were uniformly intact, but had slightly higher growth inhibition compared to PU possibly due to the presence of organic modifiers (OM. The addition of heparin into PUNCs prolonged the TGT, indicating that heparin was still active after the coating process. Cumulative heparin release profiles showed that the majority of heparin released was from loosely attached residues on the surface of coils. The addition of heparin further prolonged the TGT as compared to coatings without added heparin, but a slight decrease in heparin activity was observed in the NCs

  7. Biocompatibility of Niobium Coatings

    OpenAIRE

    René Olivares-Navarrete; Jhon Jairo Olaya; Claudia Ramírez; Sandra Elizabeth Rodil

    2011-01-01

    Niobium coatings deposited by magnetron sputtering were evaluated as a possible surface modification for stainless steel (SS) substrates in biomedical implants. The Nb coatings were deposited on 15 mm diameter stainless steel substrates having an average surface roughness of 2 mm. To evaluate the biocompatibility of the coatings three different in vitro tests, using human alveolar bone derived cells, were performed: cellular adhesion, proliferation and viability. Stainles...

  8. Characterization of the failure behavior of zinc coating on dual phase steel under tensile deformation

    International Nuclear Information System (INIS)

    Highlights: → The microcracks and voids at the zinc grain boundaries are the initial sites for the coating cracking. → The crack spacing of the fragmentally fractured zinc coating is mainly determined by the zinc grain size. → Small zinc grain size and the c-axis direction of zinc grain parallel to the zinc surface are beneficial to the mitigation of the zinc coating delamination. - Abstract: The failure behavior of hot-dip galvanized zinc coatings on dual phase steels under tensile deformation is characterized with in situ scanning electron microscopy (SEM). Under tension, the pre-existed microcracks and voids at the zinc grain boundaries propagate along the zinc grain boundaries to form crack nets within the coating, leading to a segmented fracture of the zinc coating with the crack spacing approximately equal to the zinc grain size. With further loading, the coating segments partially delaminated along the interface between the top zinc layer and the inhibition layer instead of the interface between the inhibition layer and steel substrate. As the c-axis of zinc grains trends to be normal to the tensile loading direction, the twinning deformation became more noticeable, and meanwhile the coating delamination was diminished. The transverse and incline tunneling cracks occurred in the inhibition layer with tensile deformation. The existence of the brittle FeZn13 particles on top of the inhibition layer was unfavorable to the coating adhesion.

  9. Superhard Nanocomposite Coatings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The recent development in the field of nanocomposite coatings with good mechanical properties is critically reviewed in this paper. The design principle and materials selection for the nanocomposite coatings are introduced. Different methods for the preparation of superhard nanocomposite coatings are described with emphasis on the magnetron sputtering. Based on recent theoretical and experimental results regarding the appearance of superhardness in nanocomposite coating, lattice parameter changes, crystallite size, microstructure and morphology are reviewed in detail. Also emphasized are the mechanical properties (especially on hardness) and the ways by which the properties are derived.

  10. Oxide coating development

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.

    1995-06-01

    Monolithic SiC heat exchangers and fiber-reinforced SiC-matrix composite heat exchangers and filters are susceptible to corrosion by alkali metals at elevated temperatures. Protective coatings are currently being developed to isolate the SiC materials from the corrodants. Unfortunately, these coatings typically crack and spall when applied to SiC substrates. The purpose of this task is to determine the feasibility of using a compliant material between the protective coating and the substrate. The low-modulus compliant layer could absorb stresses and eliminate cracking and spalling of the protective coatings.

  11. Microencapsulation Technology for Corrosion Mitigation by Smart Coatings

    Science.gov (United States)

    Buhrow, Jerry; Li, Wenyan; Jolley, Scott; Calle, Luz M.

    2011-01-01

    A multifunctional, smart coating for the autonomous control of corrosion is being developed based on micro-encapsulation technology. Corrosion indicators as well as corrosion inhibitors have been incorporated into microcapsules, blended into several paint systems, and tested for corrosion detection and protection effectiveness. This paper summarizes the development, optimization, and testing of microcapsules specifically designed to be incorporated into a smart coating that will deliver corrosion inhibitors to mitigate corrosion autonomously. Key words: smart coating, corrosion inhibition, microencapsulation, microcapsule, pH sensitive microcapsule, corrosion inhibitor, corrosion protection pain

  12. Innovations in coating technology.

    Science.gov (United States)

    Behzadi, Sharareh S; Toegel, Stefan; Viernstein, Helmut

    2008-01-01

    Despite representing one of the oldest pharmaceutical techniques, coating of dosage forms is still frequently used in pharmaceutical manufacturing. The aims of coating range from simply masking the taste or odour of drugs to the sophisticated controlling of site and rate of drug release. The high expectations for different coating technologies have required great efforts regarding the development of reproducible and controllable production processes. Basically, improvements in coating methods have focused on particle movement, spraying systems, and air and energy transport. Thereby, homogeneous distribution of coating material and increased drying efficiency should be accomplished in order to achieve high end product quality. Moreover, given the claim of the FDA to design the end product quality already during the manufacturing process (Quality by Design), the development of analytical methods for the analysis, management and control of coating processes has attracted special attention during recent years. The present review focuses on recent patents claiming improvements in pharmaceutical coating technology and intends to first familiarize the reader with the available procedures and to subsequently explain the application of different analytical tools. Aiming to structure this comprehensive field, coating technologies are primarily divided into pan and fluidized bed coating methods. Regarding pan coating procedures, pans rotating around inclined, horizontal and vertical axes are reviewed separately. On the other hand, fluidized bed technologies are subdivided into those involving fluidized and spouted beds. Then, continuous processing techniques and improvements in spraying systems are discussed in dedicated chapters. Finally, currently used analytical methods for the understanding and management of coating processes are reviewed in detail in the last section of the review. PMID:19075909

  13. Combustion chemical vapor deposited coatings for thermal barrier coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States). School of Materials Science and Engineering

    1995-12-31

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings. In this report, the evaluation of alumina and ceria coatings on a nickel-chromium alloy is described.

  14. Molecular Adsorber Coating

    Science.gov (United States)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  15. Rock-hard coatings

    NARCIS (Netherlands)

    Muller, M.

    2007-01-01

    Aircraft jet engines have to be able to withstand infernal conditions. Extreme heat and bitter cold tax coatings to the limit. Materials expert Dr Ir. Wim Sloof fits atoms together to develop rock-hard coatings. The latest invention in this field is known as ceramic matrix composites. Sloof has sign

  16. Coating of graphene

    NARCIS (Netherlands)

    Schneider, G.F.; Dekker, C.

    2014-01-01

    The present invention is in the field of highly crystalline graphene and coating said graphene with a layer. Said graphene may have further structures, such as nanopores, nanogaps, and nanoribbons. The coated graphene can be used for biomolecular analysis and modification, such as DNA-sequencing, as

  17. Fast-drying coating

    Science.gov (United States)

    Bartoszek, E. J.

    1978-01-01

    Nontoxic coating has excellent optical properties and can be pigmented in many different colors. It bonds well, can be applied by conventional methods, weathers well, and is self-extinguishing. Coating composition comprises latex blends of fluorocarbons, acrylic resins, stabilizers, modifiers, variety of inorganic pigments, and other additives. Suitable latex primers have also been developed from acrylic latex base.

  18. Catalytic thermal barrier coatings

    Science.gov (United States)

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  19. Charged-particle coating

    International Nuclear Information System (INIS)

    Advanced target designs require thicker (approx. 300 μm) coatings and better surface finishes that can be produced with current coating techniques. An advanced coating technique is proposed to provide maximum control of the coating flux and optimum manipulation of the shell during processing. In this scheme a small beam of ions or particles of known incident energy are collided with a levitated spherical mandrel. Precise control of the incident energy and angle of the deposition flux optimizes the control of the coating morphology while controlled rotation and noncontact support of the shell minimizes the possibility of particulate or damage generated defects. Almost infinite variability of the incident energy and material in this process provides increased flexibility of the target designs which can be physically realized

  20. Modern coating processes

    International Nuclear Information System (INIS)

    Articles collected in this volume explain both the present state of technique and current developments and problems in the environment of the following coating processes: - Hardfacing welding and soldering; - Thermal spraying; - Thin film technique (CVD, PVD); - Galvanising. Apart from basic representation of the conventional use of the different processes, both the new technological and material developments are to the fore. In this context, the purposeful post-treatment of coatings and the combination of different processes to achieve special coating properties should be mentioned. Examples of this show the hot isostatic pressing or laser melting of sprayed coatings, the simultaneous spraying and shot-blasting and the combination of galvanic and thin film techniques for the manufacture of hybrid systems. A further important group of subjects concerns the testing of various coatings. (orig.)

  1. Self-assembled hemocompatible coating on poly (vinyl chloride) surface

    Science.gov (United States)

    Zha, Zhengbao; Ma, Yan; Yue, Xiuli; Liu, Meng; Dai, Zhifei

    2009-11-01

    A stable hemocompatible coating was fabricated by consecutive alternating adsorption of iron (III) and two kinds of polysaccharides, heparin (Hep) and dextran sulfate (DS), onto poly (vinyl chloride) (PVC) surfaces via electrostatic interaction. The fluctuation of contact angles with the alternative deposition of iron (III) and polysaccharides verified the progressive buildup of the mulitilayer coating onto the PVC surface. Atomic force microscopy (AFM) analysis revealed that the PVC surfaces were completely masked by iron-polysaccharides multilayer coatings. The activated partial thromboplastin time (APTT) assay showed that both Hep/Fe 3+/Hep and DS/Fe 3+/Hep coated PVC were less thrombogenic than the uncoated one. Chromogenic assay for heparin activity proved definitively that the inhibition of locally produced thrombin was ascribed to the thromboresistance of the surface-bound heparin. Compared with the unmodified PVC surfaces, iron-polysaccharide multilayer coating presented a drastically reduced adhesion in vitro of platelets, polymorphonuclear neutrophil leukocytes (PMN) and peripheral blood mononuclear cells (PBMC). Interestingly, the DS/Fe 3+/Hep coating was found to exhibit higher hydrophilicity and stability, hence lower non-specific protein adsorption in comparison with Hep/Fe 3+/Hep coating due to the incorporation of dextran sulfate into the multilayer coating.

  2. Self-assembled hemocompatible coating on poly (vinyl chloride) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zha Zhengbao; Ma Yan; Yue Xiuli; Liu Meng [Nanobiotechnology Division, State Key Laboratory of Urban Water Resources and Environment, School of Sciences, Harbin Institute of Technology, Harbin 150001 (China); Dai Zhifei, E-mail: zhifei.dai@hit.edu.cn [Nanobiotechnology Division, State Key Laboratory of Urban Water Resources and Environment, School of Sciences, Harbin Institute of Technology, Harbin 150001 (China)

    2009-11-15

    A stable hemocompatible coating was fabricated by consecutive alternating adsorption of iron (III) and two kinds of polysaccharides, heparin (Hep) and dextran sulfate (DS), onto poly (vinyl chloride) (PVC) surfaces via electrostatic interaction. The fluctuation of contact angles with the alternative deposition of iron (III) and polysaccharides verified the progressive buildup of the mulitilayer coating onto the PVC surface. Atomic force microscopy (AFM) analysis revealed that the PVC surfaces were completely masked by iron-polysaccharides multilayer coatings. The activated partial thromboplastin time (APTT) assay showed that both Hep/Fe{sup 3+}/Hep and DS/Fe{sup 3+}/Hep coated PVC were less thrombogenic than the uncoated one. Chromogenic assay for heparin activity proved definitively that the inhibition of locally produced thrombin was ascribed to the thromboresistance of the surface-bound heparin. Compared with the unmodified PVC surfaces, iron-polysaccharide multilayer coating presented a drastically reduced adhesion in vitro of platelets, polymorphonuclear neutrophil leukocytes (PMN) and peripheral blood mononuclear cells (PBMC). Interestingly, the DS/Fe{sup 3+}/Hep coating was found to exhibit higher hydrophilicity and stability, hence lower non-specific protein adsorption in comparison with Hep/Fe{sup 3+}/Hep coating due to the incorporation of dextran sulfate into the multilayer coating.

  3. Self-assembled hemocompatible coating on poly (vinyl chloride) surface

    International Nuclear Information System (INIS)

    A stable hemocompatible coating was fabricated by consecutive alternating adsorption of iron (III) and two kinds of polysaccharides, heparin (Hep) and dextran sulfate (DS), onto poly (vinyl chloride) (PVC) surfaces via electrostatic interaction. The fluctuation of contact angles with the alternative deposition of iron (III) and polysaccharides verified the progressive buildup of the mulitilayer coating onto the PVC surface. Atomic force microscopy (AFM) analysis revealed that the PVC surfaces were completely masked by iron-polysaccharides multilayer coatings. The activated partial thromboplastin time (APTT) assay showed that both Hep/Fe3+/Hep and DS/Fe3+/Hep coated PVC were less thrombogenic than the uncoated one. Chromogenic assay for heparin activity proved definitively that the inhibition of locally produced thrombin was ascribed to the thromboresistance of the surface-bound heparin. Compared with the unmodified PVC surfaces, iron-polysaccharide multilayer coating presented a drastically reduced adhesion in vitro of platelets, polymorphonuclear neutrophil leukocytes (PMN) and peripheral blood mononuclear cells (PBMC). Interestingly, the DS/Fe3+/Hep coating was found to exhibit higher hydrophilicity and stability, hence lower non-specific protein adsorption in comparison with Hep/Fe3+/Hep coating due to the incorporation of dextran sulfate into the multilayer coating.

  4. Heritage materials and biofouling mitigation through UV-C irradiation in show caves: state-of-the-art practices and future challenges.

    Science.gov (United States)

    Borderie, Fabien; Alaoui-Sossé, Badr; Aleya, Lotfi

    2015-03-01

    Biofouling, i.e., colonization of a given substrate by living organisms, has frequently been reported for heritage materials and particularly on stone surfaces such as building facades, historical monuments, and artworks. This also concerns subterranean environments such as show caves, in which the installation of artificial light for tourism has led to the proliferation of phototrophic microorganisms. In Europe nowadays, the use of chemicals in these very sensitive environments is scrutinized and regulated by the European Union. New and environmentally friendly processes must be developed as alternative methods for cave conservation. For several years, the UV irradiation currently used in medical facilities and for the treatment of drinking water has been studied as a new innovative method for the conservation of heritage materials. This paper first presents a review of the biofouling phenomena on stone materials such as building facades and historical monuments. The biological disturbances induced by tourist activity in show caves are then examined, with special attention given to the methods and means to combat them. Thirdly, a general overview is given of the effects of UV-C on living organisms, and especially on photosynthetic microorganisms, through different contexts and studies. Finally, the authors' own experiments and findings are presented concerning the study and use of UV-C irradiation to combat algal proliferation in show caves. Both laboratory and in situ results are summarized and synthesized from their previously published works. The application of UV in caves is discussed and further experiments are proposed to enhance research in this domain. PMID:25548019

  5. Isomolybdate conversion coatings

    Science.gov (United States)

    Minevski, Zoran (Inventor); Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor)

    2002-01-01

    A conversion coating solution and process forms a stable and corrosion-resistant layer on metal substrates or layers or, more preferably, on a boehmite layer or other base conversion coating. The conversion coating process involves contacting the substrate, layer or coating with an aqueous alkali metal isomolybdate solution in order to convert the surface of the substrate, layer or coating to a stable conversion coating. The aqueous alkali metal molybdates are selected from sodium molybdate (Na.sub.2 MoO.sub.4), lithium molybdate (Li.sub.2 MoO.sub.4), potassium molybdate (K.sub.2 MoO.sub.4), or combinations thereof, with the most preferred alkali metal molybdate being sodium molybdate. The concentration of alkali metal molybdates in the solution is preferably less than 5% by weight. In addition to the alkali metal molybdates, the conversion coating solution may include alkaline metal passivators selected from lithium nitrate (LiNO.sub.3), sodium nitrate (NaNO.sub.3), ammonia nitrate (NH.sub.4 NO.sub.3), and combinations thereof; lithium chloride, potassium hexafluorozirconate (K.sub.2 ZrF.sub.6) or potassium hexafluorotitanate (K.sub.2 TiF.sub.6).

  6. Self-Cleaning Coatings and Materials for Decontaminating Field-Deployable Land and Water-Based Optical Systems

    Science.gov (United States)

    Ryan, Robert; Underwood, Lauren; Holekamp, Kara; May, George; Spiering, Bruce; Davis, Bruce

    2011-01-01

    This technology exploits the organic decomposition capability and hydrophilic properties of the photocatalytic material titanium dioxide (TiO2), a nontoxic and non-hazardous substance, to address contamination and biofouling issues in field-deployed optical sensor systems. Specifically, this technology incorporates TiO2 coatings and materials applied to, or integrated as a part of, the optical surfaces of sensors and calibration sources, including lenses, windows, and mirrors that are used in remote, unattended, ground-based (land or maritime) optical sensor systems. Current methods used to address contamination or biofouling of these optical surfaces in deployed systems are costly, toxic, labor intensive, and non-preventative. By implementing this novel technology, many of these negative aspects can be reduced. The functionality of this innovative self-cleaning solution to address the problem of contamination or biofouling depends on the availability of a sufficient light source with the appropriate spectral properties, which can be attained naturally via sunlight or supplemented using artificial illumination such as UV LEDs (light emitting diodes). In land-based or above-water systems, the TiO2 optical surface is exposed to sunlight, which catalyzes the photocatalytic reaction, facilitating both the decomposition of inorganic and organic compounds, and the activation of superhydrophilic properties. Since underwater optical surfaces are submerged and have limited sunlight exposure, supplementary UV light sources would be required to activate the TiO2 on these optical surfaces. Nighttime operation of land-based or above-water systems would require this addition as well. For most superhydrophilic self-cleaning purposes, a rainwater wash will suffice; however, for some applications an attached rainwater collector/ dispenser or other fresh water dispensing system may be required to wash the optical surface and initiate the removal of contaminates. Deployment of this

  7. Antimicrobial selenium nanoparticle coatings on polymeric medical devices

    Science.gov (United States)

    Tran, Phong A.; Webster, Thomas J.

    2013-04-01

    Bacteria colonization on medical devices remains one of the most serious complications following implantation. Traditional antibiotic treatment has proven ineffective, creating an increasingly high number of drug-resistant bacteria. Polymeric medical devices represent a significant portion of the total medical devices used today due to their excellent mechanical properties (such as durability, flexibility, etc). However, many polymers (such as polyvinyl chloride (PVC), polyurethane (PU) and silicone) become readily colonized and infected by bacteria immediately after use. Therefore, in this study, a novel antimicrobial coating was developed to inhibit bacterial growth on PVC, PU and silicone. Specifically, here, the aforementioned polymeric substrates were coated with selenium (Se) nanoparticles in situ. The Se-coated substrates were characterized using scanning electron microscopy, energy dispersive x-ray spectroscopy and bacteria assays. Most importantly, bacterial growth was significantly inhibited on the Se-coated substrates compared to their uncoated counterparts. The reduction of bacteria growth directly correlated with the density of Se nanoparticles on the coated substrate surfaces. In summary, these results demonstrate that Se should be further studied as a novel anti-bacterial polymeric coating material which can decrease bacteria functions without the use of antibiotics.

  8. Inorganic Coatings Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The inorganic Coatings Lab provides expertise to Navy and Joint Service platforms acquisition IPTs to aid in materials and processing choices which balance up-front...

  9. Application of composite protective coatings on the surface of sausages with different water content

    Directory of Open Access Journals (Sweden)

    Andrzej Tyburcy

    2010-06-01

    Full Text Available Background. Emulsion coatings on the surface of sausages counteract weight loss during storage. Therefore they could be applied instead of synthetic foils, which are used for vacuum packaging. The aim of this study was the assessment of the properties of two emulsion coatings (with different carrageenan content applied on the surface of two Polish sausages with various water content (kabanosy and frankfurterki. Material and methods. Sausages were coated with emulsions containing gelatine, kappa-carrageenan, beeswax, lard, glycerol and water. Coated and uncoated sausages were stored for 7, 14 or 21 days at the temperature of 4-6°C. After each storage period weight losses and hardness of peeled sausages, as well as colour values (L*, a*, b* and water activity of removed coatings were determined. Results. Coated sausages incurred smaller weight loss and after similar storage periods they were characterized by lower hardness in comparison with uncoated sausages. Reducing the carrageenan content decreased the consumption of emulsion for coating. However, it did not have any impact on the barrier properties of coating. Water activity of coatings decreased during storage. Their colour values also changed. Conclusions. Irrespective of water content in the sausages, emulsion coatings effectively inhibited their weight loss during storage. The coating with lower content of carrageenan could be recommended. Instability of coatings colour during storage implies the need of adding a colorant to the composition of emulsion.  

  10. Friction surfaced Stellite6 coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rao, K. Prasad; Damodaram, R. [Department of Metallurgical and Materials Engineering - Indian Institute of Technology Madras, Chennai 600 036 (India); Rafi, H. Khalid, E-mail: khalidrafi@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Ram, G.D. Janaki [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Reddy, G. Madhusudhan [Metal Joining Group, Defence Metallurgical Research Laboratory (DMRL) Kanchanbagh, Hyderabad 500 058 (India); Nagalakshmi, R. [Welding Research Institute, Bharat Heavy Electricals Limited, Tiruchirappalli 620 014 (India)

    2012-08-15

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: Black-Right-Pointing-Pointer Stellite6 used as coating material for friction surfacing. Black-Right-Pointing-Pointer Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. Black-Right-Pointing-Pointer Finer and uniformly distributed carbides in friction surfaced coatings. Black-Right-Pointing-Pointer Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  11. Nanostructured Superhydrophobic Coatings

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-03-01

    This factsheet describes a research project that deals with the nanostructured superhydrophobic (SH) powders developed at ORNL. This project seeks to (1) improve powder quality; (2) identify binders for plastics, fiberglass, metal (steel being the first priority), wood, and other products such as rubber and shingles; (3) test the coated product for coating quality and durability under operating conditions; and (4) application testing and production of powders in quantity.

  12. Spin coating apparatus

    Science.gov (United States)

    Torczynski, John R.

    2000-01-01

    A spin coating apparatus requires less cleanroom air flow than prior spin coating apparatus to minimize cleanroom contamination. A shaped exhaust duct from the spin coater maintains process quality while requiring reduced cleanroom air flow. The exhaust duct can decrease in cross section as it extends from the wafer, minimizing eddy formation. The exhaust duct can conform to entrainment streamlines to minimize eddy formation and reduce interprocess contamination at minimal cleanroom air flow rates.

  13. Advanced coated particle fuels

    International Nuclear Information System (INIS)

    The coated particle fuel (cpf) has been developed for use in high-temperature gas-cooled reactors, but it may find applications in other types of reactors. In JAERI, besides the development of cpf for High Temperature Engineering Test Reactor, conceptual studies of the cpf applications in actinide burner reactors and space reactors have been made. The conceptual design studies as well as the research and development of advanced coatings, ZrC and TiN, are reviewed. (author)

  14. Biocompatibility of Niobium Coatings

    Directory of Open Access Journals (Sweden)

    René Olivares-Navarrete

    2011-09-01

    Full Text Available Niobium coatings deposited by magnetron sputtering were evaluated as a possible surface modification for stainless steel (SS substrates in biomedical implants. The Nb coatings were deposited on 15 mm diameter stainless steel substrates having an average surface roughness of 2 mm. To evaluate the biocompatibility of the coatings three different in vitro tests, using human alveolar bone derived cells, were performed: cellular adhesion, proliferation and viability. Stainless steel substrates and tissue culture plastic were also studied, in order to give comparative information. No toxic response was observed for any of the surfaces, indicating that the Nb coatings act as a biocompatible, bioinert material. Cell morphology was also studied by immune-fluorescence and the results confirmed the healthy state of the cells on the Nb surface. X-ray diffraction analysis of the coating shows that the film is polycrystalline with a body centered cubic structure. The surface composition and corrosion resistance of both the substrate and the Nb coating were also studied by X-ray photoelectron spectroscopy and potentiodynamic tests. Water contact angle measurements showed that the Nb surface is more hydrophobic than the SS substrate.

  15. Residual stresses within sprayed coatings

    Institute of Scientific and Technical Information of China (English)

    JIANG Yi; XU Bin-shi; WANG Hai-dou

    2005-01-01

    Some important developments of residual stress researches for coating-based systems were studied. The following topics were included the sources of residual stresses in coatings: error analysis of Stoney's equation in the curvature method used for the measurement of coating residual stress, the modeling of residual stress and some analytical models for predicting the residual stresses in coatings. These topics should provide some important insights for the fail-safe design of the coating-based systems.

  16. Hydroxyapatite coatings for biomedical applications

    CERN Document Server

    Zhang, Sam

    2013-01-01

    Hydroxyapatite coatings are of great importance in the biological and biomedical coatings fields, especially in the current era of nanotechnology and bioapplications. With a bonelike structure that promotes osseointegration, hydroxyapatite coating can be applied to otherwise bioinactive implants to make their surface bioactive, thus achieving faster healing and recovery. In addition to applications in orthopedic and dental implants, this coating can also be used in drug delivery. Hydroxyapatite Coatings for Biomedical Applications explores developments in the processing and property characteri

  17. Coated particle waste form development

    International Nuclear Information System (INIS)

    Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes

  18. Effects of tallowtree seed coat on seed germination

    Institute of Scientific and Technical Information of China (English)

    LI Shu-xian; GU Hong-biao; MAO Yan; YIN Tong-ming; GAO Han-dong

    2012-01-01

    We measured physiological parameters including water uptake,in-vitro embryo germination ratio,and seed coat structure observed by scanning electron microscopy (SEM) to explore the influence of seed coat on the germination of seeds of tallow tree (Sapium sebiferum (Linn) Roxb.).Tallow tree seeds had good water permeability.We found that germination of cabbage seeds was inhibited when cabbage seeds were soaked in extracted solutions from tallow tree seed coat.Seed coat structure at the side of the radicle appeared to be a barrier to seed germination.We tested methods to break tallow tree seed dormancy.Dormancy of tallow tree seeds was overcome by soaking the seeds in 500 mg·L-1 or 1000 mg·L-1 GA3,followed by 100 days of cold stratification.

  19. Final Technical Report - Recovery Act: Organic Coatings as Encapsulants for Low Cost, High Performance PV Modules

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Hellring; Jiping Shao; James Poole

    2011-12-05

    The objective of this project was to evaluate the feasibility of utilizing PPG's commercial organic coatings systems as efficient, modernized encapsulants for low cost, high performance, thin film photovoltaic modules. Our hypothesis was that the combination of an anticorrosive coating with a more traditional barrier topcoat would mitigate many electrochemical processes that are now responsible for the significant portion of photovoltaic (PV) failures, thereby nullifying the extremely high moisture barrier requirements of currently used encapsulation technology. Nine commercially available metal primer coatings and six commercially available top coatings were selected for screening. Twenty-one different primer/top coat combinations were evaluated. The primer coatings were shown to be the major contributor to corrosion inhibition, adhesion, and barrier properties. Two primer coatings and one top coating were downselected for testing on specially-fabricated test modules. The coated test modules passed initial current leakage and insulation testing. Damp Heat testing of control modules showed visible corrosion to the bus bar metal, whereas the coated modules showed none. One of the primer/top coat combinations retained solar power performance after Damp Heat testing despite showing some delamination at the EVA/solar cell interface. Thermal Cycling and Humidity Freeze testing resulted in only one test module retaining its power performance. Failure modes depended on the particular primer/top coating combination used. Overall, this study demonstrated that a relatively thin primer/top coating has the potential to replace the potting film and backsheet in crystalline silicon-based photovoltaic modules. Positive signals were received from commercially available coatings developed for applications having performance requirements different from those required for photovoltaic modules. It is likely that future work to redesign and customize these coatings would result in

  20. Environmentally Friendly Coating Technology for Autonomous Corrosion Control

    Science.gov (United States)

    Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Johnsey, Marissa N.; Jolley, Scott T.; Pearman, Benjamin P.; Zhang, Xuejun; Fitzpatrick, Lilliana; Gillis, Mathew; Blanton, Michael; Hanna, Joshua S.; Rawlins, James W.

    2016-01-01

    This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry.

  1. Geochemistry and microbiology of iron-related well-screen encrustation and aquifer biofouling in Suffolk County, Long Island, New York

    Science.gov (United States)

    Walter, D.A.

    1997-01-01

    Iron-related well-screen encrustation and aquifer biofouling has decreased the specific capacity of several production wells in Suffolk County, N.Y., and has forced the Suffolk County Water Authority to adopt a costly well-reconditioning and replacement program. The specific-capacity declines are the result of the precipitation of iron oxyhydroxides and the growth of iron bacteria on the well screens and in the pore spaces of the surrounding formation. Mineralogic and chemical analyses indicate that the inorganic part of the encrusting material consists primarily of amorphous ferric hydroxide (Fe(OH)3 ); minor components of the material include goethite (FeOOH), hematite (Fe2 O 3 ), and quartz (SiO 2 ). The weight percent of ferric hydroxide in the material ranged from 32.3 to 98.6 percent and averaged 64.3 percent. Equilibrium modeling indicated that during pumping the well waters were supersaturated with respect to goethite, hematite, magnetite, and quartz and were under-saturated with respect to ferric hydroxide. Theoretical Eh values computed for the ferrous/ferric-iron redox couple and the oxygen/water redox couple averaged 390 millivolts and 810 millivolts, respectively, indicating that the waters were in a state of redox disequilibrium. The disequilibrium condition arises from the mixing of ground water with a low dissolved-oxygen concentration with oxygenated ground water during operation of the well. The low pH of the ground water contributes to the disequilibrium condition by slowing the rate of iron oxidation after the introduction of oxygen. Chemical and mineralogical data indicate that most of the encrusting material in the wells was deposited while the wells were shut down, probably in response to the use of treated water of higher pH to keep pump turbines wet while the wells were not in operation; the increased pH of water in the static water column increases the rate of ferrous-iron oxidation and causes the well water to become increasingly

  2. 油品泄漏对循环冷却水系统生物黏泥生长特性的影响%Effects of Oil Leakage in Circulating Cooling Water System on Biofouling Growth Characteristics

    Institute of Scientific and Technical Information of China (English)

    刘芳; 杨飞; 王飞扬; 卢宪辉; 张家权

    2012-01-01

    油品泄漏导致循环冷却水中含有大量石油烃类物质,从而影响石油炼制与化工企业生产装置的正常运行.为研究油品泄漏对循环冷却水系统的影响,以柴油作为单一泄漏油品,考察了柴油添加量及添加方式的变化对循环冷却水系统生物黏泥生长特性的影响.结果表明,低浓度的柴油对生物黏泥化学组成影响较大,柴油添加浓度增加使生物黏泥易于剥落.随着柴油添加量的增加,生物黏泥湿重有上升的趋势,脂磷质量浓度则呈现先上升后降低的趋势.泄漏方式的变化对生物黏泥生长特性影响不明显.%Oil leakage leads to a lot of petroleum hydrocarbons leaking into the circulating cooling water system, which will affect normal operation of production facilities. In order to study the impact of oil leakage on the circulating water system, diesel oil was used as the leaking oil. Effects of the diesel concentrations and addition modes on biofouling growth characteristics in circulating cooling water system were investigated. Results showed that low diesel concentrations had the rather obvious effect on biofouling chemical composition, and the increase of diesel concentration led to biofouling detachment ratio rising. With the increase of diesel concentration biofouling wet mass tended to rise, while phospholipid concentration was with the trend of first increase and then decrease. There was no obvious effect of addition modes on biofouling growth characteristics.

  3. SYNTHESIS AND ANTI-BIOFOULING PROPERTIES OF FLUORINE/SILICONE SYNERGISTICALLY MODIFIED ACRYLIC RESINS%氟硅协同改性丙烯酸树脂的合成与防污性能研究

    Institute of Scientific and Technical Information of China (English)

    孙小英; 苏友权; 金鹿江; 杭建忠; 施利毅

    2013-01-01

    以甲基丙烯酸十二氟庚酯(FMA)、甲基丙烯酸聚二甲基硅氧烷基酯(SMA)、甲基丙烯酸甲酯、丙烯酸正丁酯、甲基丙烯酸正丁酯和丙烯酸乙酯为共聚单体,通过溶液聚合反应合成出侧链含有机氟、有机硅的丙烯酸树脂.通过核磁共振氢谱(1H-NMR)、核磁共振氟谱(19F-NMR)、红外光谱(FTIR)对聚合物的结构进行了表征.通过扫描电镜(SEM)、接触角测试和生物评价等方法,探讨了FMA、SMA含量对树脂涂膜性能的影响.结果表明氟硅改性的丙烯酸树脂比单独含氟或含硅改性的丙烯酸树脂具有更低的表面能,而且氟硅改性的丙烯酸树脂涂膜比商业化的聚硅氧烷涂膜具有更好的防污性能.%The acrylic resins containing fluorine/silicone side chains were synthesized by solution copolymerization with 1H ,1H ,7H-dodecafluoroheptyl methacrylate (FMA) ,monomethacryloxyalkyl-terminated PDMS (SMA) , methyl methacrylate (MMA) , n-butyl acrylate (BA) , n-butyl methacrylate (BMA) and ethyl acrylate (EA) as the comonomers. A solution of toluene and butyl acetate ( weight ratio 1:1) was initially charged to a 250 mL four-neck flask with a condenser, a nitrogen inlet and a mechanical stirrer. The mixture was then degassed for 15 min and immersed into an oil bath at 85℃ with a slow nitrogen purge. The mixture of FMA,SMA,MMA, BA, BMA, EA and 0. 8% azobisisobutyronitrile ( AIBN) ( based on the content of the comonomers) was slowly added dropwise over 2 h. 0. 4% AIBN was slowly added after the reaction was stirred over 1. 5 h. The solution was heated to 110℃ and stirred for 2 h. The solid content of copolymer solution was 50% . The as-prepared copolymer was characterized by H-NMR, F-NMR and FTIR. The effects of FMA and SMA content on the properties of polymer coatings were investigated by scanning electron microscopy ( SEM ) and contact angle analysis. The marine antifouling properties of the materials were evaluated by laboratory assays

  4. Conductive epoxypolyamide coating composition

    Energy Technology Data Exchange (ETDEWEB)

    Mirabeau, M.N.; Rohrbacher, F.

    1991-10-01

    This patent describes a conductive coating composition comprising a film forming binder and pigment in a pigment to binder weight ratio of about 15:100 to 100:100. It comprises 40-70% by weight of an amine component having at least two reactive amine groups selected from the group consisting of an amine, polyamide, polyamido amine resin or mixtures thereof; and 30-60% by weight of an epoxy resin having at least two epoxy groups per resin molecule; wherein the pigment comprises an electrically conductive pigment that comprises silica selected from the group consisting of amorphous silica, a silica containing material or silica coated pigment, the silica being in association with a two- dimensional network of antimony-containing tin oxide crystallites in which the antimony content ranges from about 1-30% by weight of the tin oxide and the composition forms a coating having a surface conductivity of at least 100 Ransburg units.

  5. Electrophoretic Deposition of Chitosan Coatings Modified with Gelatin Nanospheres To Tune the Release of Antibiotics.

    Science.gov (United States)

    Song, Jiankang; Chen, Qiang; Zhang, Yang; Diba, Mani; Kolwijck, Eva; Shao, Jinlong; Jansen, John A; Yang, Fang; Boccaccini, Aldo R; Leeuwenburgh, Sander C G

    2016-06-01

    Orthopedic and dental implants are increasingly used in the medical field in view of their high success rates. Implant-associated infections, however, still occur and are difficult to treat. To combat these infections, the application of an active coating to the implant surface is advocated as an effective strategy to facilitate sustained release of antibacterial drugs from implant surfaces. Control over this release is, however, still a major challenge. To overcome this problem, we deposited composite coatings composed of a chitosan matrix containing gelatin nanospheres loaded with antibiotics onto stainless steel plates by means of the electrophoretic deposition technique. The gelatin nanospheres were distributed homogeneously throughout the coatings. The surface roughness and wettability of the coatings could be tuned by a simple adjustment of the weight ratio between the gelatin nanospheres and chitosan. Vancomycin and moxifloxacin were released in sustained and burst-type manners, respectively, while the coatings were highly cytocompatible. The antibacterial efficacy of the coatings containing different amounts of antibiotics was tested using a zone of inhibition test against Staphylococcus aureus, which showed that the coatings containing moxifloxacin exhibited an obvious inhibition zone. The coatings containing a high amount of vancomycin were able to kill bacteria in direct contact with the implant surface. These results suggest that the antibacterial capacity of metallic implants can be tuned by orthogonal control over the release of (multiple) antibiotics from electrophoretically deposited composite coatings, which offers a new strategy to prevent orthopedic implant-associated infections. PMID:27167424

  6. HA-Coated Implant

    DEFF Research Database (Denmark)

    Daugaard, Henrik; Søballe, Kjeld; Bechtold, Joan E

    2014-01-01

    The goal of osseointegration of orthopedic and dental implants is the rapid achievement of a mechanically stable and long lasting fixation between living bone and the implant surface. In total joint replacements of cementless designs, coatings of calcium phosphates were introduced as a means...... of improving the fixation of implants. Of these, hydroxyapatite (HA) is the most widely used and most extensively investigated. HA is highly osseoconductive, and the positive effect is well documented in both basic and long-term clinical research [1–6]. This chapter describes experimental and clinical studies...... evaluating bone-implant fixation with HA coatings....

  7. Preparation of hydrophobic coatings

    Science.gov (United States)

    Branson, Eric D.; Shah, Pratik B.; Singh, Seema; Brinker, C. Jeffrey

    2009-02-03

    A method for preparing a hydrophobic coating by preparing a precursor sol comprising a metal alkoxide, a solvent, a basic catalyst, a fluoroalkyl compound and water, depositing the precursor sol as a film onto a surface, such as a substrate or a pipe, heating, the film and exposing the film to a hydrophobic silane compound to form a hydrophobic coating with a contact angle greater than approximately 150.degree.. The contact angle of the film can be controlled by exposure to ultraviolet radiation to reduce the contact angle and subsequent exposure to a hydrophobic silane compound to increase the contact angle.

  8. Methods and means for coating paper by film coating

    NARCIS (Netherlands)

    van der Maarel, Marc; Ter Veer, Arend Berend Cornelis; Vrieling-Smit, Annet; Delnoye, Pierre

    2015-01-01

    This invention relates to the field of paper coating, more in particular to means and methods for providing paper with at least one layer of pigment using film coating to obtain a well printable surface. Provided is a method for preparing coated paper comprising the steps of: a) providing a pigmente

  9. Nanostructural haemocompatible coatings for the internal side of artificial blood vessels

    Science.gov (United States)

    Trembecka-Wojciga, K.; Major, R.; Lackner, J. M.; Butruk-Raszeja, B.; Sanak, M.; Major, B.

    2016-03-01

    The main goal of the work was to elaborate low thrombogenicity of surface inside tube-like elements for cardiovascular system support by combination of low-temperature glow discharge and hydrogel coatings to inhibit blood-clotting cascade activation. A large share of amorphous phase silicon was observed in the microstructure analysis. The crystalline elements were uniformly distributed in the amorphous structure. Combination of low thickness, the proper microstructure and density of the coatings provided a highly flexible nature of the whole system. The blood-material interaction was analyzed in vitro in dynamic conditions by using a designed and fabricated novel blood flow simulator. Coatings deposited by the glow discharge expressed good hemocopatibile properties. The use of hydrogel coatings did not reduce coagulation parameter. Hydrogel coatings did not improve the hemocompatibility of the surface modified with carbon based coatings. Modification of surface with hydrogel resulted in further increased risk of hemolysis.

  10. Corrosion behavior of niobium coated 304 stainless steel in acid solution

    Science.gov (United States)

    Pan, T. J.; Chen, Y.; Zhang, B.; Hu, J.; Li, C.

    2016-04-01

    The niobium coating is fabricated on the surface of AISI Type 304 stainless steel (304SS) by using a high energy micro arc alloying technique in order to improvecorrosion resistance of the steel against acidic environments. The electrochemical corrosion resistance of the niobium coating in 0.7 M sulfuric acid solutions is evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and the open circuit potential versus time. Electrochemical measurements indicate that the niobium coating increases the free corrosion potential of the substrate by 110 mV and a reduction in the corrosion rate by two orders of magnitude compared to the substrate alone. The niobium coating maintains large impedance and effectively offers good protection for the substrate during the long-term exposure tests, which is mainly ascribed to the niobium coating acting inhibiting permeation of corrosive species. Finally, the corresponding electrochemical impedance models are proposed to elucidate the corrosion resistance behavior of the niobium coating in acid solutions.

  11. ZnO/Al2O3 coatings for the photoprotection of polycarbonate

    International Nuclear Information System (INIS)

    ZnO and ZnO/Al2O3 thin films were deposited by r.f. magnetron sputtering on polycarbonate (PC) films in order to protect this polymer against photodegradation. The composition, structure and optical properties of the ceramic coatings were characterised. CO2-plasma treatments were applied to PC in order to improve the coating adhesion. The PC surface energy was characterised by wettability measurements and the chemical bonds were analysed by XPS. It was found that ZnO coatings improve the stability of PC to UV radiations and that an intermediate alumina coating inhibits the photocatalytic oxidation of PC at the PC/ZnO interface. Additionally an external alumina coating brings a high hardness to the coating

  12. Controlled release of environmentally friendly antifouling agents from marine coatings

    DEFF Research Database (Denmark)

    Olsen, Stefan Møller

    maling, og sjette kapitel omhandler de eksperimenter, der er blevet udført med henblik på at teste forskellige frigivelseshastighed af hydrogenperoxid på biofouling. Uorganiske peroxider er blevet testet som nye antifouling maling ingredienser, og frigivelsen af hydrogenperoxid fra malinger indeholdende...... hydrogenperoxid på biofouling er blevet testet, og hydrogenperoxid frigivet som eneste biocid fra en ikke polerende overflade kræver en frigivelseshastighed på et sted mellem 225 og 2800 μg/(cm2 •dag) for at holde overfladen fri for biofouling, når denne er placeret i Jyllinge havn i Danmark i løbet af ni uger om...

  13. Carbon coatings for medical implants

    OpenAIRE

    K. Bakowicz-Mitura; P. Couvrat; I. Kotela; P. Louda; D. Batory; J. Grabarczyk

    2007-01-01

    Purpose: In this paper we report in vitro and in vivo results of Nanocrystalline Diamond Coatings whichare used in medicine onto medical implants The very important property of carbon coatings is the protectionliving organism against the metalosis. Different medical implants with complicated shapes are covering byNanocrystalline Diamond Coatings by RF dense plasma CVD.Design/methodology/approach: 1) Material characterizations of deposited coatings have been evaluated by using:Transmission Ele...

  14. Foam coating of filtration media

    OpenAIRE

    Johansson, Mirva

    2015-01-01

    The objective of this thesis was to find out if foam coating could be applied to non-woven filtration media. The goal was to increase collection efficiency without significantly decreasing air permeability. In the theoretical part, foams and their characteristics were the centre of attention. Coating in general and, of course, foam coating were also studied. The empirical part consisted of series of foaming experiments and pilot scale coating experiments. In the foaming experiments differ...

  15. Optical coatings for fiber lasers

    Institute of Scientific and Technical Information of China (English)

    HONG Dong-mei; ZHU Zhen; YUE Wei

    2005-01-01

    Fiber laser is the future development direction for the high energy lasers. This paper describs two kinds of optical coatings for fiber laser, including long and short wave pass filters. The one characteristic of fiber laser coatings lies in that coatings should separate two closely wavelength light including laser pump wavelength (980 nm) and laser irradiation wavelength(1 050~1 100 nm). At the same time, the coatings should have high laser damage threshold.

  16. TABLET COATING TECHNIQUES: CONCEPTS AND RECENT TRENDS

    Directory of Open Access Journals (Sweden)

    Gupta Ankit

    2012-09-01

    Full Text Available Tablet coating is a common pharmaceutical technique of applying a thin polymer-based film to a tablet or a granule containing active pharmaceutical ingredients (APIs. Solid dosage forms are coated for a number of reasons, the most important of which is controlling the release profiles. The amount of coating on the surface of a tablet is critical to the effectiveness of the oral dosage form. Tablets are usually coated in horizontal rotating pans with the coating solution sprayed onto the free surface of the tablet bed. The advantages of tablet coating are taste masking, odour masking, physical and chemical protection, protects the drug from the gastric environment etc. There are various techniques for tablet coating such as sugar coating, film coating, and enteric coating. Recent trends in pharmaceutical technologies are the development of coating methods which overcomes the various disadvantages associated with solvent based coatings. In these latest technologies coating materials are directly coated onto the surface of solid dosage forms without using any solvent. Various solventless coatings are available such as electrostatic dry coating, magnetically assisted impaction coating, compression coating, hot melt coating, powder coating, and supercritical fluid coating. Supercell Coating Technology is a revolutionary tablet coating that accurately deposits controlled amounts of coating materials on tablets even if they are extremely hygroscopic or friable. Magnetically assisted impaction coating, electrostatic dry coating in solventless coatings, aqueous film coating and Supercell coating technology are also available recent technique of coating. An ideal tablet should be free from any visual defect or functional defect. The advancements and innovations in tablet manufacture have not decreased the problems, often encountered in the production, instead have increased the problems, mainly because of the complexities of tablet presses; and/or the

  17. Tribological characterization of selected hard coatings

    OpenAIRE

    Karlsson, Patrik

    2009-01-01

    Hard coatings are often used for protection of tool surfaces due to coating properties like low friction and high wear resistance. Even though many of the hard coatings have been tested for wear, it is important to try new wear test setups to fully understand tribological mechanisms and the potential of hard coatings. Few experiments have been performed with dual-coated systems where the sliding contact surfaces are coated with the same, or different, hard coating. The dual-coated system coul...

  18. Coatings and Tints of Spectacle Lenses

    OpenAIRE

    H. Zeki Büyükyıldız

    2012-01-01

    Spectacle lenses are made of mineral or organic (plastic) materials. Various coatings and tints are applied to the spectacle lenses according to the characteristic of the lens material, and for the personal needs and cosmetic purpose. The coatings may be classified in seven groups: 1) Anti-reflection coatings, 2) Hard coatings, 3) Clean coat, 4) Mirror coatings, 5) Color tint coating (one of coloring processes), 6) Photochromic coating (one of photochromic processes), and 7) Anti-fog...

  19. Waterborne coatings for videotape

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, S.; Fan, H.; Gogineni, N.; Jacobs, B.; Harrell, J.W.; Jefcoat, I.A.; Lane, A.M.; Nikles, D.E. [Univ. of Alabama, Tuscaloosa, AL (United States). Center for Materials for Information Technology

    1995-10-01

    Magnetic tape provides a low-cost, high-density information storage medium. There is a problem, however, because current manufacturing technology uses organic solvents to apply the magnetic wailing to the film. Here the authors describe a waterborne formulation that shows promise as a technology for pollution prevention. The organic solvents used in magnetic tape coating formulations include 2-butanone (methylethyl ketone [MEK]), 4-methyl-2-pentanone (methyl-iso-butyl ketone [MIBK]), tetrahydrofuran, toluene, and cyclohexanone. These solvents present an occupational hazard to the workers and emissions hazard to the environment. The authors developed a new waterborne coating formulation and prepared magnetic tape in a pilot coating trial. The tape has mechanical and magnetic properties comparable to those of the commercial VHS tape. There is a clear economic and environmental incentive to consider adopting this waterborne process for magnetic tape manufacture. This process is not commercial, and a development effort by a tape manufacturer is required to bring it to commercial reality. They have not addressed the important issue of long-term reliability of the materials package, an object of current research. However, they have made a case for a reexamination of the use of waterborne coating formulations by the magnetic tape industry.

  20. Niobium coating techniques

    CERN Document Server

    Calatroni, S

    2008-01-01

    We will give a historical overview of the niobium on copper sputtering technology for RF cavities and discuss the main advantages and disadvantages with respect to bulk niobium cavities. Some highlights of the present understanding will be given and some recent developments in the coating technology will be discussed.

  1. Mechanically Invisible Polymer Coatings

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a composition comprising encapsulated particles in a polymeric material. The composition comprises a continuous phase and a discontinuous phase incorporated therein, wherein the continuous phase comprises a first polymeric material and wherein the discontinuous ph...... invisible polymer coatings....

  2. Coatings for transport industry

    Directory of Open Access Journals (Sweden)

    Krzysztof LUKASZKOWICZ

    2014-09-01

    Full Text Available The investigations concerned structural analysis, as well as mechanical properties and wear resistant of MeN/DLC double-layer coating deposited by hybrid PVD/PACVD method. In sliding dry friction conditions, after the break-in time, the friction coefficient for the investigated elements is set in the range between 0.03-0.06.

  3. Surface Charges and Shell Crosslinks Each Play Significant Roles in Mediating Degradation, Biofouling, Cytotoxicity and Immunotoxicity for Polyphosphoester-based Nanoparticles

    Science.gov (United States)

    Elsabahy, Mahmoud; Zhang, Shiyi; Zhang, Fuwu; Deng, Zhou J.; Lim, Young H.; Wang, Hai; Parsamian, Perouza; Hammond, Paula T.; Wooley, Karen L.

    2013-11-01

    The construction of nanostructures from biodegradable precursors and shell/core crosslinking have been pursued as strategies to solve the problems of toxicity and limited stability, respectively. Polyphosphoester (PPE)-based micelles and crosslinked nanoparticles with non-ionic, anionic, cationic, and zwitterionic surface characteristics for potential packaging and delivery of therapeutic and diagnostic agents, were constructed using a quick and efficient synthetic strategy, and importantly, demonstrated remarkable differences in terms of cytotoxicity, immunotoxicity, and biofouling properties, as a function of their surface characteristics and also with dependence on crosslinking throughout the shell layers. For instance, crosslinking of zwitterionic micelles significantly reduced the immunotoxicity, as evidenced from the absence of secretions of any of the 23 measured cytokines from RAW 264.7 mouse macrophages treated with the nanoparticles. The micelles and their crosslinked analogs demonstrated lower cytotoxicity than several commercially-available vehicles, and their degradation products were not cytotoxic to cells at the range of the tested concentrations. PPE-nanoparticles are expected to have broad implications in clinical nanomedicine as alternative vehicles to those involved in several of the currently available medications.

  4. Biofouling and microbial corrosion problem in the thermo-fluid heat exchanger and cooling water system of a nuclear test reactor.

    Science.gov (United States)

    Rao, T S; Kora, Aruna Jyothi; Chandramohan, P; Panigrahi, B S; Narasimhan, S V

    2009-10-01

    This article discusses aspects of biofouling and corrosion in the thermo-fluid heat exchanger (TFHX) and in the cooling water system of a nuclear test reactor. During inspection, it was observed that >90% of the TFHX tube bundle was clogged with thick fouling deposits. Both X-ray diffraction and Mossbauer analyses of the fouling deposit demonstrated iron corrosion products. The exterior of the tubercle showed the presence of a calcium and magnesium carbonate mixture along with iron oxides. Raman spectroscopy analysis confirmed the presence of calcium carbonate scale in the calcite phase. The interior of the tubercle contained significant iron sulphide, magnetite and iron-oxy-hydroxide. A microbiological assay showed a considerable population of iron oxidizing bacteria and sulphate reducing bacteria (10(5) to 10(6) cfu g(-1) of deposit). As the temperature of the TFHX is in the range of 45-50 degrees C, the microbiota isolated/assayed from the fouling deposit are designated as thermo-tolerant bacteria. The mean corrosion rate of the CS coupons exposed online was approximately 2.0 mpy and the microbial counts of various corrosion causing bacteria were in the range 10(3) to 10(5) cfu ml(-1) in the cooling water and 10(6) to 10(8) cfu ml(-1) in the biofilm. PMID:20183117

  5. Adsorption of a PEO-PPO-PEO triblock copolymer on metal oxide surfaces with a view to reducing protein adsorption and further biofouling.

    Science.gov (United States)

    Yang, Y; Poleunis, C; Románszki, L; Telegdi, J; Dupont-Gillain, C C

    2013-01-01

    Abstract Biomolecule adsorption is the first stage of biofouling. The aim of this work was to reduce the adsorption of proteins on stainless steel (SS) and titanium surfaces by modifying them with a poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO)-PEO triblock copolymer. Anchoring of the central PPO block of the copolymer is known to be favoured by hydrophobic interaction with the substratum. Therefore, the surfaces of metal oxides were first modified by self-assembly of octadecylphosphonic acid. PEO-PPO-PEO preadsorbed on the hydrophobized surfaces of titanium or SS was shown to prevent the adsorption of bovine serum albumin (BSA), fibrinogen and cytochrome C, as monitored by quartz crystal microbalance (QCM). Moreover, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry were used to characterize the surfaces of the SS and titanium after competitive adsorption of PEO-PPO-PEO and BSA. The results show that the adsorption of BSA is well prevented on hydrophobized surfaces, in contrast to the surfaces of native metal oxides.

  6. 碳钢在海水环境中的腐蚀和污损特性研究%Corrosion and Biofouling Character of Carbon Steel in Seawater

    Institute of Scientific and Technical Information of China (English)

    杨海洋; 黄桂桥

    2013-01-01

    Change of corrosion rate of carbon steels in seawater was discussed. Corrosion and biofouling character of carbon steels in seawater were summarized. The result showed that corrosion rate of the carbon steel exposed to seawater decreases with time, which is stable after one or two years of exposure;the corrosion course can be divided into the process dynamics controlled stage, the oxygen diffusion controlled stage, the growth of fouling organism controlled stage, and microbiological corrosion controlled stage.%讨论了碳钢材料在海水环境中的腐蚀速率随时间的变化情况,总结了碳钢在海水中不同暴露阶段的腐蚀和生物污损特性。结果显示,碳钢在海水中的腐蚀速度随时间延长而下降,暴露1~2年后腐蚀速率变化不显著,其腐蚀过程可分为腐蚀过程控制阶段、氧扩散控制阶段、污损生物成长控制阶段和微生物腐蚀控制阶段等4个阶段。

  7. Active coatings technologies for tailorable military coating systems

    Science.gov (United States)

    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.

  8. Characterization of Encapsulated Corrosion Inhibitors for Environmentally Friendly Smart Coatings

    Science.gov (United States)

    Pearman, B. P.; Calle, L. M.; Zhang, X.; Li, W.; Buhrow, J. W.; Johnsey, M. N.; Montgomery, E. L.; Fitzpatrick, L.; Surma, J. M.

    2015-01-01

    The NASA Kennedy Space Center's Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion indicators, inhibitors and self-healing agents. This allows the incorporation of autonomous corrosion control functionalities, such as corrosion detection and inhibition as well as the self-healing of mechanical damage, into coatings. This paper presents technical details on the characterization of inhibitor-containing particles and their corrosion inhibitive effects using electrochemical and mass loss methods. Three organic environmentally friendly corrosion inhibitors were encapsulated in organic microparticles that are compatible with desired coatings. The release of the inhibitors from the microparticles in basic solution was studied. Fast release, for immediate corrosion protection, as well as long-term release for continued protection, was observed. The inhibition efficacy of the inhibitors, incorporated directly and in microparticles, on carbon steel was evaluated. Polarization curves and mass loss measurements showed that, in the case of 2MBT, its corrosion inhibition effectiveness was greater when it was delivered from microparticles.

  9. Coat protein activation of alfalfa mosaic virus replication is concentration dependent.

    Science.gov (United States)

    Guogas, Laura M; Laforest, Siana M; Gehrke, Lee

    2005-05-01

    Alfalfa mosaic virus (AMV) and ilarvirus RNAs are infectious only in the presence of the viral coat protein; therefore, an understanding of coat protein's function is important for defining viral replication mechanisms. Based on in vitro replication experiments, the conformational switch model states that AMV coat protein blocks minus-strand RNA synthesis (R. C. Olsthoorn, S. Mertens, F. T. Brederode, and J. F. Bol, EMBO J. 18:4856-4864, 1999), while another report states that coat protein present in an inoculum is required to permit minus-strand synthesis (L. Neeleman and J. F. Bol, Virology 254:324-333, 1999). Here, we report on experiments that address these contrasting results with a goal of defining coat protein's function in the earliest stages of AMV replication. To detect coat-protein-activated AMV RNA replication, we designed and characterized a subgenomic luciferase reporter construct. We demonstrate that activation of viral RNA replication by coat protein is concentration dependent; that is, replication was strongly stimulated at low coat protein concentrations but decreased progressively at higher concentrations. Genomic RNA3 mutations preventing coat protein mRNA translation or disrupting coat protein's RNA binding domain diminished replication. The data indicate that RNA binding and an ongoing supply of coat protein are required to initiate replication on progeny genomic RNA transcripts. The data do not support the conformational switch model's claim that coat protein inhibits the initial stages of viral RNA replication. Replication activation may correlate with low local coat protein concentrations and low coat protein occupancy on the multiple binding sites present in the 3' untranslated regions of the viral RNAs. PMID:15827190

  10. Formation of Silicide Coating layer on U-Mo Powder

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ji Min; Kim, Sunghwan; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    High-density U-Mo alloys are regarded as promising candidates for advanced research reactor fuel as they have shown stable irradiation performance when compared to other uranium alloys and compounds. However, interaction layer formation between the U-Mo alloys and Al matrix degrades the irradiation performance of U-Mo Dispersion fuel. Therefore, the addition of Ti in U-Mo alloys, the addition of Si in a Al matrix, and silicide or nitride coating on the surface of U-Mo particles have been proposed to inhibit the interaction layer growth. In this study, U-Mo alloy powder was produced using a centrifugal atomization method. In addition, silicide coating layers were fabricated by several mixing process changes on the surface of the U-Mo particles. The coated powders were characterized by using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDAX). Decreased annealing duration did not affect the forming of silicide coating layers on the surface of U-7wt%Mo powders. The variation in the mixing ratio between U-7wt%Mo and Si powders had an effect on the quality of silicide coating on the U-7wt%Mo powders. The weight of Si powders should be smaller than that of U-7wt%Mo powders for better silicide coating when it comes to the mixing ratio.

  11. Catalytic cracking of endothermic fuels in coated tube reactor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Suspensoid of HZSM-5 or HY zeolites mixed with a self-made ceramic-like binder was coated on the inner wall of a tubular reactor by gas-aided fluid displacement technology.The coated zeolites were characterized by means of X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM).The coating thickness is 10-20 μm and the particle size of the zeolites is in the range of 1-5 μm.In the coated reactor,cracking of endothermic fuels including n-dodecane and aviation fuel RP-3 was carried out separately under supercritical conditions at 600℃ and 625℃ to investigate their heat sinks and conversion of catalytic reactions.For the reaction catalyzed by HY (25% mass fraction) coating,the heat sink capacity of ndodecane are 815.7 and 901.9 kJ/kg higher than that of the bare tube at 600℃ and at 625℃,respectively.Conversion of n-dodecane also increases from 42% to 60% at 600℃ and from 66% to 80% at 625℃.The coated zeolite can significantly inhibit the carbon deposition during supercritical cracking reactions.

  12. Antibacterial Efficacy of a New Gentamicin-Coating for Cementless Prostheses Compared to Gentamicin-Loaded Bone Cement

    NARCIS (Netherlands)

    Neut, Danielle; Dijkstra, Rene J. B.; Thompson, Jonathan I.; van der Mei, Henny C.; Busscher, Henk J.

    2011-01-01

    Cementless prostheses are increasingly popular but require alternative prophylactic measures than the use of antibiotic-loaded bone cements. Here, we determine the 24-h growth inhibition of gentamicin-releasing coatings from grit-blasted and porous-coated titanium alloys, and compare their antibacte

  13. Effect of nano-TiO2 particles size on the corrosion resistance of alkyd coating

    International Nuclear Information System (INIS)

    The coating system containing various sizes (∼10, 50, 100, 150 nm) of nano-TiO2 were prepared and investigated for corrosion protection of carbon steel in 1.0 M H2SO4 using polarization, EIS and transmission electron microscopy (TEM) techniques. It was found that nano-TiO2 particles improved the corrosion resistance of alkyd coatings. The corrosion resistance occurs via physical adhesion on the metal surface. O2 and H2O permeability of coating decreased with decrease in the nano-TiO2 size. The inhibition efficiency was found to increase with decreasing the size of nano-TiO2 and with decreasing the temperature. - Highlights: • Nano-TiO2 coating were prepared and used for corrosion protection of C-steel. • Nano-TiO2 particles in coating are effective to improve the corrosion resistance. • Nano-TiO2 coating inhibit both anodic and cathodic reactions. • Corrosion inhibition efficiency increases with decrease in the size of nano-TiO2. • O2 and H2O permeability of coating decreased with decrease in the nano-TiO2 size

  14. Hybrid nanostructured coatings for corrosion protection of base metals: a sustainability perspective

    Science.gov (United States)

    Dennis, Robert V.; Patil, Vikas; Andrews, Justin L.; Aldinger, Jeffrey P.; Yadav, Ganapati D.; Banerjee, Sarbajit

    2015-03-01

    In this topical review article, we attempt to capture recent advances in the development of sustainable hybrid nanocomposite coatings for the corrosion inhibition of structural metals. Spurred primarily by the urgent imperative of replacing hexavalent chromium but also driven by concerns regarding the environmental impact of organic solvents, materials criticality considerations, the need to maintain structural integrity and function under extreme environments, and a renewed impetus towards lightweighting, the design of new coating concepts has seen an explosion of activity. We discuss varying modes of corrosion inhibition and the drive towards multicomponent nanostructured coatings that synergistically unite multiple modes of corrosion inhibition within a single coating system. Nanocomposite coatings in which nanoparticles of one phase are dispersed within a continuous phase, usually a polymeric matrix, provide a modular design approach to multifunctional coatings provided fundamental challenges such as dispersion and compatibility can be resolved. By dint of their high surface-to-volume ratios, the incorporation of nanoparticles profoundly modifies the adjacent polymeric matrix, giving rise to an ‘interphase’ region with modified properties, at relatively low filler loadings. The implications of incorporating metallic, porous metal oxide, and carbon nanomaterials (graphene and carbon nanotubes) within polymeric matrices are explored with an emphasis on active corrosion inhibition. The availability of high-quality nanoparticles that are either electroactive (e.g., metals, graphene, carbon nanotubes, etc.) or are capable of serving as reservoirs for active corrosion inhibitors (e.g., porous silicon oxide, layered double hydroxides, halloysite) provides unprecedented functionality and opportunities for multifunctional coatings. The review emphasizes mechanistic considerations where these have been elucidated with a view towards developing systematic design

  15. Orthopaedic metal devices coated with a novel antiseptic dye for the prevention of bacterial infections.

    Science.gov (United States)

    Bahna, Paul; Dvorak, Tanya; Hanna, Hend; Yasko, Alan W; Hachem, Ray; Raad, Issam

    2007-05-01

    Gendine is a novel antiseptic dye with broad-spectrum antimicrobial activity that may be used to coat plastics and metal devices. Our objective was to determine the efficacy of gendine-coated orthopaedic metal devices in preventing methicillin-resistant Staphylococcus aureus (MRSA) colonisation. Stainless steel and titanium Schanz rods were coated with gendine. The zone of inhibition (ZoI) around the rods with and without gamma-irradiation was determined by a modified Kirby-Bauer method. A previously published bioprosthetic biofilm colonisation model, modified Kuhn's method, was used to determine the adherence of MRSA to coated and uncoated rods, with and without irradiation, after insertion into bovine bone and after 3 months shelf life followed by 2 weeks of immersion in serum. The gendine-coated Schanz metal rods showed a net ZoI of 16 mm against MRSA before and after irradiation. Gendine-coated rods showed no biofilm formation (0 colony-forming units (CFU)), which was a significant reduction (P5000 CFU). Coated rods exposed to high-dose gamma-irradiation and coated rods drilled into bone also showed significant efficacy (P<0.001) in preventing biofilm adherence. After 2 weeks, gendine-coated rods maintained significant durability (P<0.01), resulting in 90% reduction in MRSA biofilm adherence compared with uncoated control rods. Results indicate that gendine-coated metal rods are highly efficacious in the prevention of MRSA biofilm.

  16. Optimization of an aqueous tablet-coating process containing carboxymethylated Cassia fistula gum.

    Science.gov (United States)

    Rai, Parshu Ram; Tiwary, Ashok Kumar; Rana, Vikas

    2012-06-01

    The present investigation was aimed at developing and optimizing a simple aqueous tablet-coating formulation and its process. 5-Fluorouracil (5-FU) was used to ascertain the relative lipophilic/hydrophilic behavior of the coating system. Optimization was performed by evaluating the adhesive force strength and cohesive force strength of the tablet coat using a texture analyzer. The in vitro release of 5-FU was found to decrease with an increase in (tablet surface-coat) adhesive force strength. The (tablet-tablet) cohesive force strength was reduced by the addition of magnesium silicate to the coating solution. The addition of magnesium silicate (0.2% w/v) to the carboxymethyl Cassia fistula gum-chitosan (CCG-CH) coating surface significantly inhibited the release of 5-FU possibly due to an increase in the hydrophobic character of the coated tablet surface. This was possible by coating cohesive force strength reduction coating compositions (CCG-CH (70:30) and 0.3% magnesium silicate). Further, the FTIR-ATR and DSC analyses suggested the pivotal role of magnesium silicate in modifying the release of 5-FU from CCG-CH-coated tablets due to hydrogen bonding of its Si-O-Si or Mg-O groups with -OH moieties of CCG-CH.

  17. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-06-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  18. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  19. Infrared optical coatings in SITP

    Institute of Scientific and Technical Information of China (English)

    LIU Ding-quan; ZHANG Feng-shan

    2005-01-01

    Infrared optical coatings in SITP (Shanghai Institute of Technical Physics) mainly cover the spectrum range from 0.7 μm to 15 μm, and visible and near-UV range are also been included. The coatings are mainly used for metal-reflectance mirrors, Anti-reflection(AR) lens and windows, filters, and dichroic beam splitters. Coatings passed some dependability tests. These optical coated devices usually consist in a remote observing instrument. Most coating materials are commercial products. And one kind of special material PbTe is made by ourselves. Some main results of our research department are reported.

  20. In vitro hemocompatibility and cytocompatibility of dexamethasone-eluting PLGA stent coatings

    International Nuclear Information System (INIS)

    Highlights: • Biodegradable dexamethasone-eluting PLGA stent coatings were developed. • Stent coatings can withstand the compressive and tensile strains without cracking. • Stent coatings presented favorable release kinetic for the lesion site. • Stent coatings can effectively inhibit the adhesion and activation of platelets. • Stent coatings can effectively inhibit the proliferation of SMC. - Abstract: Drug-eluting stents (DESs) have been an important breakthrough for interventional cardiology applications since 2002. Though successful in reducing restenosis, some adverse clinical problems still emerged, which were mostly caused by the bare-metal stents and non-biodegradable polymer coatings, associated with the delayed endothelialization process. In this study, dexamethasone-loaded poly (lactic-co-glycolic acid) (PLGA) coatings were developed to explore the potential application of dexamethasone-eluting stents. Dexamethasone-eluting PLGA stents were prepared using ultrasonic atomization spray method. For other tests like stability and cytocompatibility and hemocompatibility tests, dexamethasone loaded coatings were deposited on 316L SS wafers. Fourier transform-infrared spectroscopy (FT-IR) results demonstrated that there was no chemical reaction between PLGA and dexamethasone. The balloon expansion experiment and surface morphology observation suggested that the stent coatings were smooth and uniform, and could also withstand the compressive and tensile strains imparted without cracking after stent expansion. The drug release behavior in vitro indicated that dexamethasone existed burst release within 1 day, but it presented linear release characteristics after 6 days. In vitro platelets adhesion, activation test and APTT test were also done, which showed that after blending dexamethasone into PLGA, the hemocompatibility was improved. Besides, dexamethasone and dexamethasone-loaded PLGA coatings could significantly inhibit the attachment and

  1. In vitro hemocompatibility and cytocompatibility of dexamethasone-eluting PLGA stent coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiang; Liu, Yang; Luo, Rifang; Chen, Si; Li, Xin; Yuan, Shuheng; Wang, Jin, E-mail: jinxxwang@263.net; Huang, Nan

    2015-02-15

    Highlights: • Biodegradable dexamethasone-eluting PLGA stent coatings were developed. • Stent coatings can withstand the compressive and tensile strains without cracking. • Stent coatings presented favorable release kinetic for the lesion site. • Stent coatings can effectively inhibit the adhesion and activation of platelets. • Stent coatings can effectively inhibit the proliferation of SMC. - Abstract: Drug-eluting stents (DESs) have been an important breakthrough for interventional cardiology applications since 2002. Though successful in reducing restenosis, some adverse clinical problems still emerged, which were mostly caused by the bare-metal stents and non-biodegradable polymer coatings, associated with the delayed endothelialization process. In this study, dexamethasone-loaded poly (lactic-co-glycolic acid) (PLGA) coatings were developed to explore the potential application of dexamethasone-eluting stents. Dexamethasone-eluting PLGA stents were prepared using ultrasonic atomization spray method. For other tests like stability and cytocompatibility and hemocompatibility tests, dexamethasone loaded coatings were deposited on 316L SS wafers. Fourier transform-infrared spectroscopy (FT-IR) results demonstrated that there was no chemical reaction between PLGA and dexamethasone. The balloon expansion experiment and surface morphology observation suggested that the stent coatings were smooth and uniform, and could also withstand the compressive and tensile strains imparted without cracking after stent expansion. The drug release behavior in vitro indicated that dexamethasone existed burst release within 1 day, but it presented linear release characteristics after 6 days. In vitro platelets adhesion, activation test and APTT test were also done, which showed that after blending dexamethasone into PLGA, the hemocompatibility was improved. Besides, dexamethasone and dexamethasone-loaded PLGA coatings could significantly inhibit the attachment and

  2. BIODEGRADABLE COATING FROM AGATHIS ALBA

    Directory of Open Access Journals (Sweden)

    NORYAWATI MULYONO

    2012-11-01

    Full Text Available The adhesive property of copal makes it as a potential coating onto aluminum foil to replace polyethylene. This research aimed to develop copal-based coating. The coating was prepared by extracting the copal in ethyl acetate and dipping the aluminium foil in ethyl acetate soluble extract of copal. The characterization of coating included its thickness, weight, thermal and chemical resistance, and biodegradation. The results showed that the coating thickness and weight increased as the copal concentration and dipping frequency increased. Thermal resistance test showed that the coating melted after being heated at 110°C for 30 min. Copal-based coating wasresistant to acidic solution (pH 4.0, water, and coconut oil, but was deteriorated in detergent 1% (w/v and basic solution (pH 10.0. Biodegradability test using Pseudomonas aeruginosa showed weight reduction of 76.82% in 30 days.

  3. Methods for Coating Particulate Material

    Science.gov (United States)

    Littman, Howard (Inventor); Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor)

    2013-01-01

    Methods and apparatus for coating particulate material are provided. The apparatus includes a vessel having a top and a bottom, a vertically extending conduit having an inlet in the vessel and an outlet outside of the vessel, a first fluid inlet in the bottom of the vessel for introducing a transfer fluid, a second fluid inlet in the bottom of the vessel for introducing a coating fluid, and a fluid outlet from the vessel. The method includes steps of agitating a material, contacting the material with a coating material, and drying the coating material to produce a coated material. The invention may be adapted to coat aerogel beads, among other materials. A coated aerogel bead and an aerogel-based insulation material are also disclosed.

  4. Surface modification of TiO2 coatings by Zn ion implantation for improving antibacterial activities

    Indian Academy of Sciences (India)

    Xiaobing Zhao; Jiashen Yang; Jing You

    2016-02-01

    TiO$_2$ coating has been widely applied in orthopaedic and dental implants owing to its excellent mechanical and biological properties. However, one of the biggest complications of TiO$_2$ coating is implant-associated infections. The aim of this work is to improve the antibacterial activity of plasma-sprayed TiO$_2$ coatings by plasma immersion ion implantation (PIII) using zinc (Zn) ions. Results indicate that the as-sprayed TiO$_2$ coating is mainly composed of rutile phase. Zn-PIII modification does not change the phase compositions and the surface morphologies of TiO$_2$ coatings, while change their hydrophilicity. Zn-implanted TiO$_2$ coatings can inhibit the growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and the ability to inhibit S. aureus is greater than that to E. coli. Zn ion release and reactive oxygen species may be attributed to improving the antibacterial activity of TiO$_2$ coating. Therefore, Zn-PIII TiO$_2$ coatings on titanium suggest promising candidates for orthopaedic and dental implants.

  5. Evaluation of SmCo and SmCoN magnetron sputtering coatings for SOFC interconnect applications

    Science.gov (United States)

    Wu, Junwei; Li, Chengming; Johnson, Christopher; Liu, Xingbo

    Cobalt or cobalt containing coatings are promising for SOFC interconnect applications because of their high conductivity. We have investigated SmCo and SmCoN coatings deposited by magnetron sputtering from a SmCo (5% Sm) target on to Crofer 22 APU substrates. The composition, structure, surface morphology, and electrical conductivity of the coated substrates were characterized by SEM/EDX, XRD and ASR measurements. Addition of Sm enhances the oxidation resistance and the Cr retention capability of the coatings. The use of nitride as a precursor stabilizes Sm during oxidation of the films, thus inhibiting diffusion of Fe, resulting in a more compact coating and lowering ASR. The combined advantages of Sm addition to cobalt and the use of a nitride as a precursor, makes SmCoN coatings a promising new interconnect coating material.

  6. Use of hydrogel coating to improve the performance of implanted glucose sensors.

    Science.gov (United States)

    Yu, Bazhang; Wang, Chunyan; Ju, Young Min; West, Leigh; Harmon, Julie; Moussy, Yvonne; Moussy, Francis

    2008-03-14

    In order to protect implanted glucose sensors from biofouling, novel hydrogels (146-217% water by mass) were developed based on a copolymer of hydroxyethyl methacrylate (HEMA) and 2,3-dihydroxypropyl methacrylate (DHPMA). The porosity and mechanical properties of the hydrogels were improved using N-vinyl-2-pyrrolidinone (VP) and ethyleneglycol dimethacrylate (EGDMA). The results of SEM and DSC FT-IT analyses showed that the hydrogel (VP30) produced from a monomeric mixture of 34.5% HEMA, 34.5% DHPMA, 30% VP and 1% EDGMA (mol%) had an excellent pore structure, high water content at swelling equilibrium (W eq=166% by mass) and acceptable mechanical properties. Two kinds of VP30-coated sensors, Pt/GOx/VP30 and Pt/GOx/epoxy-polyurethane (EPU)/VP30 sensors were examined in glucose solutions during a period of 4 weeks. The Pt/GOx/VP30 sensors produced large response currents but the response linearity was poor. Therefore, further studies were focused on the Pt/GOx/EPU/VP30 sensors. With a diffusion-limiting epoxy-polyurethane membrane, the linearity was improved (2-30 mM) and the response time was within 5 min. Eight Pt/GOx/EPU/VP30 sensors were subcutaneously implanted in rats and tested once per week over 4 weeks. All of the implanted sensors kept functioning for at least 21 days and 3 out of 8 sensors still functioned at day 28. Histology revealed that the fibrous capsules surrounding hydrogel-coated sensors were thinner than those surrounding Pt/GOx/EPU sensors after 28 days of implantation. PMID:18182283

  7. Coat proteins isolated from clathrin coated vesicles can assemble into coated pits

    OpenAIRE

    1989-01-01

    Isolated human fibroblast plasma membranes that were attached by their extracellular surface to a solid substratum contained numerous clathrin coated pits that could be removed with a high pH buffer (Moore, M.S., D.T. Mahaffey, F.M. Brodsky, and R.G.W. Anderson. 1987. Science [Wash. DC]. 236:558-563). When these membranes were incubated with coat proteins extracted from purified bovine coated vesicles, new coated pits formed that were indistinguishable from native coated pits. Assembly was de...

  8. Antithrombogenic Polymer Coating.

    Science.gov (United States)

    Huang, Zhi Heng; McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

    2003-01-21

    An article having a non-thrombogenic surface and a process for making the article are disclosed. The article is formed by (i) coating a polymeric substrate with a crosslinked chemical combination of a polymer having at least two amino substituted side chains, a crosslinking agent containing at least two crosslinking functional groups which react with amino groups on the polymer, and a linking agent containing a first functional group which reacts with a third functional group of the crosslinking agent, and (ii) contacting the coating on the substrate with an antithrombogenic agent which covalently bonds to a second functional group of the linking agent. In one example embodiment, the polymer is a polyamide having amino substituted alkyl chains on one side of the polyamide backbone, the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl, the linking agent is a polyhydrazide and the antithrombogenic agent is heparin.

  9. Acrylic purification and coatings

    CERN Document Server

    ,

    2012-01-01

    Radon (Rn) and its decay daughters are a well-known source of background in direct WIMP detection experiments, as either a Rn decay daughter or an alpha particle emitted from a thin inner surface layer of a detector could produce a WIMP-like signal. Different surface treatment and cleaning techniques have been employed in the past to remove this type of contamination. A new method of dealing with the problem has been proposed and used for a prototype acrylic DEAP-1 detector. Inner surfaces of the detector were coated with a layer of ultra pure acrylic, meant to shield the active volume from alphas and recoiling nuclei. An acrylic purification technique and two coating techniques are described: a solvent-borne (tested on DEAP-1) and solvent-less (being developed for the full scale DEAP-3600 detector).

  10. Permeability of edible coatings.

    Science.gov (United States)

    Mishra, B; Khatkar, B S; Garg, M K; Wilson, L A

    2010-01-01

    The permeabilities of water vapour, O2 and CO2 were determined for 18 coating formulations. Water vapour transmission rate ranged from 98.8 g/m(2).day (6% beeswax) to 758.0 g/m(2).day (1.5% carboxymethyl cellulose with glycerol). O2 permeability at 14 ± 1°C and 55 ± 5% RH ranged from 1.50 to 7.95 cm(3)cm cm(-2)s(-1)Pa(-1), with CO2 permeability 2 to 6 times as high. Permeability to noncondensable gases (O2 and CO2) was higher for hydrophobic (peanut oil followed by beeswax) coatings as compared to hydrophilic (whey protein concentrate and carboxymethyl cellulose).

  11. Superelastic Orthopedic Implant Coatings

    Science.gov (United States)

    Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew

    2014-07-01

    The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.

  12. Small-angle neutron scattering studies of mineralization on BSA coated citrate capped gold nanoparticles used as a model surface for membrane scaling in RO wastewater desalination.

    Science.gov (United States)

    Dahdal, Y N; Pipich, V; Rapaport, H; Oren, Y; Kasher, R; Schwahn, D

    2014-12-23

    Bovine serum albumin (BSA) coated on citrate capped gold nanoparticles (BSA-GNPs) was exposed to a simulated wastewater effluent (SSE) in order to study the mineralization and thereby mimic scaling at biofouled membranes of reverse osmosis (RO) wastewater desalination plants. RO is a leading technology of achieving freshwater quality as it has the capability of removing both dissolved inorganic salts and organic contaminants from tertiary wastewater effluents. The aim was to better understand one of the major problems facing this technology which is fouling of the membranes, mainly biofouling and scaling by calcium phosphate. The experiments were performed using the small-angle neutron scattering (SANS) technique. The nanoparticles, GNPs, stabilized by the citrate groups showed 30 Å large particles having a homogeneous distribution of gold and citrate with a gold volume fraction of the order of 1%. On the average two BSA monomers are grafted at 2.4 GNPs. The exposed BSA-GNPs to SSE solution led to immediate mineralization of stable composite particles of the order of 0.2 μm diameter and a mineral volume fraction between 50% and 80%. The volume fraction of the mineral was of the order of 10(-5), which is roughly 3 times larger but an order of magnitude smaller than the maximum possible contents of respectively calcium phosphate and calcium carbonate in the SSE solution. Considering the extreme low solubility product of calcium phosphate, we suggest total calcium phosphate and partially (5-10%) calcium carbonate formation in the presence of BSA-GNPs.

  13. Environmentally regulated aerospace coatings

    Science.gov (United States)

    Morris, Virginia L.

    1995-01-01

    Aerospace coatings represent a complex technology which must meet stringent performance requirements in the protection of aerospace vehicles. Topcoats and primers are used, primarily, to protect the structural elements of the air vehicle from exposure to and subsequent degradation by environmental elements. There are also many coatings which perform special functions, i.e., chafing resistance, rain erosion resistance, radiation and electric effects, fuel tank coatings, maskants, wire and fastener coatings. The scheduled promulgation of federal environmental regulations for aerospace manufacture and rework materials and processes will regulate the emissions of photochemically reactive precursors to smog and air toxics. Aerospace organizations will be required to identify, qualify and implement less polluting materials. The elimination of ozone depleting chemicals (ODC's) and implementation of pollution prevention requirements are added constraints which must be addressed concurrently. The broad categories of operations affected are the manufacture, operation, maintenance, and repair of military, commercial, general aviation, and space vehicles. The federal aerospace regulations were developed around the precept that technology had to be available to support the reduction of organic and air toxic emissions, i.e., the regulations cannot be technology forcing. In many cases, the regulations which are currently in effect in the South Coast Air Quality Management District (SCAQMD), located in Southern California, were used as the baseline for the federal regulations. This paper addresses strategies used by Southern California aerospace organizations to cope with these regulatory impacts on aerospace productions programs. All of these regulatory changes are scheduled for implementation in 1993 and 1994, with varying compliance dates established.

  14. Biomimetic implant coatings.

    Science.gov (United States)

    Eisenbarth, E; Velten, D; Breme, J

    2007-02-01

    Biomaterials and tissue engineering technologies are becoming increasingly important in biomedical practice, particularly as the population ages. Cellular responses depend on topographical properties of the biomaterial at the nanometer scale. Structures on biomaterial surfaces are used as powerful tools to influence or even control interactions between implants and the biological system [; ]. The influence of nanometer sized surface structures on osteoblastlike cell interactions was tested with niobium oxide coatings on polished titanium slices (cp-Ti grade 2). The aim of the study was to investigate the influence of nanoscopic surface structures on osteoblast interactions in order to support collagen I production and cell adhesion. The coatings were done by means of the sol-gel process. The surface structure was adjusted by annealing of the metaloxide ceramic coatings due to temperature depended crystal growth. The applied annealing temperatures were 450, 550 and 700 degrees C for 1 h, corresponding to Ra-numbers of 7, 15 and 40 nm. The surfaces were characterized by means of AFM, DTA/TG, diffractometry and white light interferometry. The cell reactions were investigated concerning adhesion kinetics, migration, spreading, cell adhesion, and collagen I synthesis. The smooth surface (Ra=7 nm) resulted in the fastest cell anchorage and cell migration. The closest cell adhesion was reached with the surface structure of Ra=15 nm. The roughest surface (Ra=40 nm) impedes the cell migration as well as a proper spreading of the cells. The best results concerning cell adhesion and spreading was reached with an intermediate surface roughness of Ra=15 nm of the niobium oxide coating on cp-titanium slices. PMID:16828342

  15. Thermal barrier coating materials

    Directory of Open Access Journals (Sweden)

    David R. Clarke

    2005-06-01

    Full Text Available Improved thermal barrier coatings (TBCs will enable future gas turbines to operate at higher gas temperatures. Considerable effort is being invested, therefore, in identifying new materials with even better performance than the current industry standard, yttria-stabilized zirconia (YSZ. We review recent progress and suggest that an integrated strategy of experiment, intuitive arguments based on crystallography, and simulation may lead most rapidly to the development of new TBC materials.

  16. Corrosion-Activated Micro-Containers for Environmentally Friendly Corrosion Protective Coatings

    Science.gov (United States)

    Li, Wenyan; Buhrow, J. W.; Zhang, X.; Johnsey, M. N.; Pearman, B. P.; Jolley, S. T.; Calle, L. M.

    2016-01-01

    This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry. The NASA Kennedy Space Centers Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion

  17. Edison's vacuum coating patents

    International Nuclear Information System (INIS)

    Among the over one thousand patents bearing Thomas A. Edison's name are several for vacuum coating processes including chemical vapor deposition, evaporation, and sputter deposition. Beginning in 1880 Edison applied for patents that described carbon deposition processes that would now be called pyrolytic chemical vapor deposition. In 1884 Edison applied for a patent (granted in 1894) that described coating by evaporation in a vacuum by direct resistance heating or arc heating using a continuous current. Edison called the process 'electro vacuous deposition'. He prophetically wrote, 'the uses of the invention are almost infinite'. Edison also employed sputter deposition and in 1900 applied for a patent on a 'Process of Coating Phonograph Records'. Issued in 1902, the patent describes using a 'silent or brush electrical discharge' produced by an induction coil. The National Phonograph Company, one of Edison's many enterprises, used the sputtering process to deposit a thin layer of gold on wax phonograph cylinder masters that could then be electroplated to form molds to mass produce celluloid duplicates. The method was used for 20 years, from 1901 to 1921. It enabled the reproduction of cylinder grooves less than 0.001 in. deep at a density of 200 grooves per in. From 1913 to 1921, 10-in.-diameter Edison Diamond Disc phonograph records were made using the same method. Sputtering was abandoned in 1927, as it could not be scaled up to produce the 12 in. disks that were then introduced

  18. Surface coating of plastics

    International Nuclear Information System (INIS)

    Electron beam hardening technology has been used mainly for the cross-linking reaction of plastic materials, but recently attention has been paid to the easiness of handling due to the reduction of equipment size and as the countermeasures for preventing atmospheric pollution caused by solvent type paints, Particularly the authors notices the excellent surface properties of electron beam-hardened coatings themselves, and advanced the research and development as one means to give functions to plastic films. In this paper, the transcription foil films having hardness and blur-preventing films are reported. The transcription process for the transcription foils on which hard coating is applied beforehand is shown. The electron beam hardening hard coating was provided next to a supporting film, and its material was polymer or oligomer/polyfunctional monomer/additive. As a primer layer, acrylic polymer was used. The procedure of making transcription foils is explained, and it is important to form uniform, smooth films. If the formation of water drops on surfaces can be prevented, blur does not arise. By heightening the hydrophilicity of material surfaces with electron beam, it may be done. By the selection of the irradiation amount of electron beam and materials, the balance must be maintained. (K.I.)

  19. for zeolite coating

    Directory of Open Access Journals (Sweden)

    Carlos Renato Rambo

    2006-01-01

    Full Text Available Biotemplating is the processing of microcellular ceramics by reproduction of natural morphologies, where the microstructural features of the biotemplate are maintained in the biomorphic ceramic. Different biotemplates with distinct pore anatomies were used to produce biomorphic supports for the zeolite coating: wood, cardboard, sea-sponge and sisal. The biomorphic ceramics were produced by distinguished processing routes: Al-gas infiltration-reaction, liquid-metal infiltration, dip-coating and sol-gel synthesis, in order to produce nitrides, carbides and oxides, depending on the processing conditions. The zeolite coating was performed by hydrothermal growth of MFI-type (Silicalite-1 and ZSM-5 zeolite crystals onto the internal pore walls of the biomorphic templates. The final biomorphic ceramic-zeolite composites were physically characterized, evaluated in terms of their gas adsorption capabilities and correlated to their microstructure and specific pore anatomy. The combination of the properties of the biomorphic ceramics with the adsorption properties of zeolites results in materials with distinct properties as potential candidates for adsorption and catalytic applications due to their characteristic porosity, molecular sieving capabilities and high thermo-mechanical strength.

  20. Cell multiplication following partial enzymatic removal of surface coat.

    Science.gov (United States)

    Wyroba, E

    1978-08-01

    Treatment of Paramecium aurelia with trypsin or pronase (1 mg per 10(5) cells, at 0 to 4 degrees C) partially removes the surface coat and modifies significantly multiplication of cells. The division rate after 24 hours of cultivation is diminished approximately twice in the case of pronase-treated cells and 1.5 for tyrpsin-digested ciliates as compared with the control. On the second day the division rate increases rapidly and number of cell divisions exceeds the values observed in the control. After 72 hours of cultivation the division rate in both untreated and enzyme-treated cells is almost the same. It is concluded that the observed inhibition of cell fission results from the enzymatic removal of the surface coat--the integrity of this surface coat seems to be necessary in the process of cell division. The influence of environmental factors on the rate of growth is presented.