| 1. |
- Abramova, Anna, 1990, et al.
(författare)
-
The complex barnacle perfume: identification of waterborne pheromone homologues in Balanus improvisus and their differential expression during settlement
- 2019
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 35:4, s. 416-428
-
Tidskriftsartikel (refereegranskat)abstract
- A key question in barnacle biology is the nature of cues that induce gregarious settlement. One of the characterised cues is the waterborne settlement pheromone (WSP). This study aimed to identify WSP homologues in Balanus improvisus and to investigate their expression during settlement. Six WSP homologues were identified, all containing an N-terminal signal peptide, a conserved core region, and a variable C-terminus comprising several -GR- and -HDDH- motifs. The B. improvisus WSP homologues were expressed in all settlement stages but showed different expression patterns. The homologue most similar to the B. amphitrite WSP was the most abundant and was constantly expressed during settlement. In contrast, several of the other WSP homologues showed the greatest expression in the juvenile stage. The presence of several WSP homologues suggests the existence of a pheromone mix, where con-specificity might be determined by a combination of sequence characteristics and the concentration of the individual components.
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| 2. |
- Al-Fori, M., et al.
(författare)
-
Antifouling properties of zinc oxide nanorod coatings
- 2014
-
Ingår i: Biofouling. - : Taylor & Francis. - 0892-7014 .- 1029-2454. ; 30:7, s. 871-882
-
Tidskriftsartikel (refereegranskat)abstract
- In laboratory experiments, the antifouling (AF) properties of zinc oxide (ZnO) nanorod coatings were investigated using the marine bacterium Acinetobacter sp. AZ4C, larvae of the bryozoan Bugula neritina and the microalga Tetraselmis sp. ZnO nanorod coatings were fabricated on microscope glass substrata by a simple hydrothermal technique using two different molar concentrations (5 and 10 mM) of zinc precursors. These coatings were tested for 5 h under artificial sunlight (1060 W m(-2) or 530 W m(-2)) and in the dark (no irradiation). In the presence of light, both the ZnO nanorod coatings significantly reduced the density of Acinetobacter sp. AZ4C and Tetraselmis sp. in comparison to the control (microscope glass substratum without a ZnO coating). High mortality and low settlement of B. neritina larvae was observed on ZnO nanorod coatings subjected to light irradiation. In darkness, neither mortality nor enhanced settlement of larvae was observed. Larvae of B. neritina were not affected by Zn2+ ions. The AF effect of the ZnO nanorod coatings was thus attributed to the reactive oxygen species (ROS) produced by photocatalysis. It was concluded that ZnO nanorod coatings effectively prevented marine micro and macrofouling in static conditions.
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| 3. |
- Andersson, Annika, et al.
(författare)
-
Adhesion and removal of dormant, heat-activated, and germinated spores of three strains of Bacillus cereus
- 1998
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Ingår i: Biofouling (Print). - 0892-7014 .- 1029-2454. ; 13:1, s. 51-67
-
Tidskriftsartikel (refereegranskat)abstract
- As the spores of Bacillus cereus are known to be very adhesive, the cleaning processes used to eliminate them are often inefficient. This study investigated how adhesion and removal of spores varied among strains of the species B. cereus. The adhesion and removal of spores during their life cycle were also examined. Spores of three different strains of B. cereus, viz. NVH 61, 1AM 1110 and NCTC 2599, were used. IAM 1110 spores adhered in greater numbers than spores of the other two strains and were the most hydrophobic; four times as many spores of this strain adhered than of the least adhesive spores, NCTC 2599. Spores of both these strains have an exosporium and appendages, but as the relative hydrophobicity varies, there are probably differences in their chemical composition. It was also found that dormant spores were 33-48% more adhesive than germinated spores. There were no obvious differences in adhesion between dormant and heat-activated spores. Up to 80% of the germinated spores could be removed from the surfaces tested. Dormant and heat-activated spores on the other hand were difficult to remove from the surfaces. When siliconized glass surfaces were coated with milk, germinated spores were still the easiest to remove but the difference was not as marked as before. Therefore, this work suggests that cleaning processes should take into consideration factors that boost spore germination in order to improve the cleaning.
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| 4. |
- Arnebrant, Thomas, et al.
(författare)
-
Lubricating Properties of the Initial Salivary Pellicle
- 2003
-
Ingår i: Biofouling (Print). - : Harwood Academic Publishers. - 0892-7014 .- 1029-2454. ; 19:6, s. 365-369
-
Tidskriftsartikel (refereegranskat)abstract
- The role of saliva in the oral cavity is manifold; an important function is to serve as lubricant between hard (enamel) and soft (mucosal) tissues. Intraoral lubrication is of crucial importance in order to maintain functions such as deglutition, mastication and the faculty of speech. A large number of people suffer from impaired salivary functions, displaying symptoms such as 'dry mouth'. This results in a need for methods to assess the lubricating properties of both native saliva and potential artificial saliva formulations. Here, normal as well as lateral forces, acting between adsorbed salivary films, have been measured for the first time by means of colloidal probe atomic force microscopy (AFM). It was found that the presence of salivary pellicles between hard surfaces reduces the friction coefficient by a factor of 20. This reduction of friction is consistent with the long-range purely repulsive nature of the normal forces acting between the salivary films. The lubricating mechanism is presumably based on a full separation of the sliding surfaces by the salivary films. The friction between salivary films has been investigated at normal loads that cover the clinical jaw closing forces, and it can be concluded that the lubricating properties are maintained within this load interval. The present study indicates the usefulness of colloidal probe AFM, which offers a direct and quantitative measure of lubrication at a molecular level, in the study of biotribological phenomena. In particular, the results obtained here may have implications for the development of saliva substitutes.
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| 5. |
- Aroonsang, Watcharapong, et al.
(författare)
-
Influence of substratum hydrophobicity on salivary pellicles : organization or composition?
- 2014
-
Ingår i: Biofouling (Print). - : Taylor & Francis. - 0892-7014 .- 1029-2454. ; 30:9, s. 1123-1132
-
Tidskriftsartikel (refereegranskat)abstract
- Different physico-chemical properties (eg adsorption kinetics, thickness, viscoelasticity, and mechanical stability) of adsorbed salivary pellicles depend on different factors, including the properties (eg charge, roughness, wettability, and surface chemistry) of the substratum. Whether these differences in the physico-chemical properties are a result of differences in the composition or in the organization of the pellicles is not known. In this work, the influence of substratum wettability on the composition of the pellicle was studied. For this purpose, pellicles eluted from substrata of different but well-characterized wettabilities were examined by means of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that substratum hydrophobicity did not have a major impact on pellicle composition. In all substrata, the major pellicle components were found to be cystatins, amylases and large glycoproteins, presumably mucins. In turn, interpretation of previously reported data based on the present results suggests that variations in substratum wettability mostly affect the organization of the pellicle components.
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| 6. |
- Arvidsson, Anna, 1973, et al.
(författare)
-
Characterisation of structures in salivary secretion film formation. An experimental study with atomic force microscopy
- 2004
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 20:3, s. 181-8
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to characterise the structure dynamics of pure salivary secretions retained on controlled surfaces with different surface energies in the early stage of salivary film formation. Germanium prisms prepared to have either low surface energy or medium surface energy were incubated in fresh secretions of either human parotid saliva (HPS) or human submandibular/sublingual saliva (HSMSLS) for 15, 90, and 180 min. After controlled rinsing with distilled water, the surfaces were air dried and thereafter imaged with atomic force microscopy (AFM). The amount of adsorbed material and the size of the structures detected increased with increased saliva exposure time. The film thicknesses varied from 10 to 150 nm, and both HPS and HSMSLS films contained structures with diameters varying from 40 nm to 2 microm. Some of these were clustered into special formations. The HPS films exhibited a more granular morphology than the HSMSLS films. Furthermore, branched lines were detected on the low surface energy germanium prisms incubated in saliva. The results indicate that exposure time, surface energy, and type of salivary secretion all are factors affecting the adsorption characteristics of salivary films.
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| 7. |
- Bellas, Juan, et al.
(författare)
-
Sublethal effects of a new antifouling candidate on lumpfish (Cyclopterus lumpus L.) and Atlantic cod (Gadus morhua L.) larvae
- 2005
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 21:3-4, s. 207-216
-
Tidskriftsartikel (refereegranskat)abstract
- Sublethal effects of medetomidine, a new generation antifouling compound, on lumpfish ( Cyclopterus lumpus L.) and cod ( Gadus morhua L.) larvae were examined. The effects on respiration rate and on colour adaptation of newly hatched larvae were assessed after 24-96 h exposure. Exposure of lumpfish larvae to the experimental concentrations resulted in a significant decrease in respiration rate (Lowest Observed Effect Concentration (LOEC) = 5-10 nM) and in the percentage of dark larvae (LOEC = 4 nM). However, no effects on respiration rate of cod larvae were detected. In addition to lumpfish larvae being affected at low concentrations of medetomidine, a reversibility of the effects was observed when 96 h-exposed larvae were incubated in clean seawater for 24-48 h. Considerations relating to the future commercialisation of medetomidine for antifouling purposes are discussed.
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| 8. |
- Bellas, Juan
(författare)
-
Toxicity assessment of the antifouling compound zinc pyrithione using early developmental stages of the ascidian Ciona intestinalis
- 2005
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 21:5-6, s. 289-296
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated the toxicity of zinc pyrithione (Zpt) on the early stages of development of the ascidian Ciona intestinalis . Larval morphological abnormalities were studied after the exposure of C. intestinalis embryos at different stages of development. The median effective concentrations (EC50 ) ranged from 226-590 nM. The larval settlement stage was the most sensitive to Zpt. Toxic effects of Zpt on larval settlement were detected at 9 nM (EC10). The inhibition of C. intestinalis embryonic development was also used to study the loss of toxicity in Zpt solutions exposed to direct sunlight and laboratory UV light. The results showed that the toxicity of Zpt solutions decreased but did not disappear after 4 h exposure to direct sunlight (EC50 = 484 nM) or UV light (EC50 = 453 nM), compared to control Zpt solutions prepared in dark conditions. On the basis of the present data, predicted no effect concentrations of Zpt to C. intestinalis larvae are lower than predicted environmental concentrations of Zpt in certain polluted areas and therefore, may pose a risk to C. intestinalis populations.
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| 9. |
- Berg, I. C. H., et al.
(författare)
-
Lubricating properties of the initial salivary pellicle - an AFM Study
- 2003
-
Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 19:6, s. 365-369
-
Tidskriftsartikel (refereegranskat)abstract
- The role of saliva in the oral cavity is manifold; an important function is to serve as lubricant between hard (enamel) and soft (mucosal) tissues. Intraoral lubrication is of crucial importance in order to maintain functions such as deglutition, mastication and the faculty of speech. A large number of people suffer from impaired salivary functions, displaying symptoms such as 'dry mouth'. This results in a need for methods to assess the lubricating properties of both native saliva and potential artificial saliva formulations. Here, normal as well as lateral forces, acting between adsorbed salivary films, have been measured for the first time by means of colloidal probe atomic force microscopy (AFM). It was found that the presence of salivary pellicles between hard surfaces reduces the friction coefficient by a factor of 20. This reduction of friction is consistent with the long-range purely repulsive nature of the normal forces acting between the salivary films. The lubricating mechanism is presumably based on a full separation of the sliding surfaces by the salivary films. The friction between salivary films has been investigated at normal loads that cover the clinical jaw closing forces, and it can be concluded that the lubricating properties are maintained within this load interval. The present study indicates the usefulness of colloidal probe AFM, which offers a direct and quantitative measure of lubrication at a molecular level, in the study of biotribological phenomena. In particular, the results obtained here may have implications for the development of saliva substitutes.
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| 10. |
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| 11. |
- Brooke, Darby G., et al.
(författare)
-
Antifouling activity of portimine, select semisynthetic analogues, and other microalga-derived spirocyclic imines
- 2018
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 34:8, s. 950-961
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. A range of natural products from marine invertebrates, bacteria and fungi have been assessed as leads for nature-inspired antifouling (AF) biocides, but little attention has been paid to microalgal-derived compounds. This study assessed the AF activity of the spirocyclic imine portimine (1), which is produced by the benthic mat-forming dinoflagellate Vulcanodinium rugosum. Portimine displayed potent AF activity in a panel of four macrofouling bioassays (EC 50 0.06–62.5 ng ml −1 ), and this activity was distinct from that of the related compounds gymnodimine-A (2), 13-desmethyl spirolide C (3), and pinnatoxin-F (4). The proposed mechanism of action for portimine is induction of apoptosis, based on the observation that portimine inhibited macrofouling organisms at developmental stages known to involve apoptotic processes. Semisynthetic modification of select portions of the portimine molecule was subsequently undertaken. Observed changes in bioactivity of the resulting semisynthetic analogues of portimine were consistent with portimine’s unprecedented 5-membered imine ring structure playing a central role in its AF activity.
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| 12. |
- Dahlstrom, M., et al.
(författare)
-
Affinity states of biocides determine bioavailability and release rates in marine paints
- 2015
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Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 31:2, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- A challenge for the next generation marine antifouling (AF) paints is to deliver minimum amounts of biocides to the environment. The candidate AF compound medetomidine is here shown to be released at very low concentrations, ie ng ml(-1) day(-1). Moreover, the release rate of medetomidine differs substantially depending on the formulation of the paint, while inhibition of barnacle settlement is independent of release to the ambient water, ie the paint with the lowest release rate was the most effective in impeding barnacle colonisation. This highlights the critical role of chemical interactions between biocide, paint carrier and the solid/aqueous interface for release rate and AF performance. The results are discussed in the light of differential affinity states of the biocide, predicting AF activity in terms of a high surface affinity and preserved bioavailability. This may offer a general framework for the design of low-release paint systems using biocides for protection against biofouling on marine surfaces.
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| 13. |
- Davis, R. A., et al.
(författare)
-
Evaluation of natural resveratrol multimers as marine antifoulants
- 2023
-
Ingår i: Biofouling. - : Taylor and Francis Ltd.. - 0892-7014 .- 1029-2454. ; 39:8, s. 775-784
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Tidskriftsartikel (refereegranskat)abstract
- In the current study we investigate the antifouling potential of three polyphenolic resveratrol multimers (-)-hopeaphenol, vaticanol B and vatalbinoside A, isolated from two species of Anisoptera found in the Papua New Guinean rainforest. The compounds were evaluated against the growth and settlement of eight marine microfoulers and against the settlement and metamorphosis of Amphibalanus improvisus barnacle cyprids. The two isomeric compounds (-)-hopeaphenol and vaticanol B displayed a high inhibitory potential against the cyprid larvae metamorphosis at 2.8 and 1.1 mu M. (-)-Hopeaphenol was also shown to be a strong inhibitor of both microalgal and bacterial adhesion at submicromolar concentrations with low toxicity. Resveratrol displayed a lower antifouling activity compared to the multimers and had higher off target toxicity against MCR-5 fibroblasts. This study illustrates the potential of natural products as a valuable source for the discovery of novel antifouling leads with low toxicity.
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| 14. |
- Di Fino, A., et al.
(författare)
-
Correlation between surface chemistry and settlement behaviour in barnacle cyprids (Balanus improvisus)
- 2014
-
Ingår i: Biofouling (Print). - : Taylor andamp; Francis: STM, Behavioural Science and Public Health Titles. - 0892-7014 .- 1029-2454. ; 30:2, s. 143-152
-
Tidskriftsartikel (refereegranskat)abstract
- In laboratory-based biofouling assays, the influence of physico-chemical surface characteristics on barnacle settlement has been tested most frequently using the model organism Balanus amphitrite (= Amphibalanus amphitrite). Very few studies have addressed the settlement preferences of other barnacle species, such as Balanus improvisus (= Amphibalanus improvisus). This study aimed to unravel the effects of surface physico-chemical cues, in particular surface-free energy (SFE) and surface charge, on the settlement of cyprids of B. improvisus. The use of well-defined surfaces under controlled conditions further facilitates comparison of the results with recent similar data for B. amphitrite. Zero-day-old cyprids of B. improvisus were exposed to a series of model surfaces, namely self-assembled monolayers (SAMs) of alkanethiols with varying end-groups, homogenously applied to gold-coated polystyrene (PS) Petri dishes. As with B. amphitrite, settlement of cyprids of B. improvisus was influenced by both SFE and charge, with higher settlement on low-energy (hydrophobic) surfaces and negatively charged SAMs. Positively charged SAMs resulted in low settlement, with intermediate settlement on neutral SAMs of similar SFE. In conclusion, it is demonstrated that despite previous suggestions to the contrary, these two species of barnacle show similar preferences in response to SFE; they also respond similarly to charge. These findings have positive implications for the development of novel antifouling (AF) coatings and support the importance of consistency in substratum choice for assays designed to compare surface preferences of fouling organisms.
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| 15. |
- Dorkhan, Marjan, et al.
(författare)
-
Crystalline anatase-rich titanium can reduce adherence of oral streptococci
- 2014
-
Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 30:6, s. 751-759
-
Tidskriftsartikel (refereegranskat)abstract
- Dental implant abutments that emerge through the mucosa are rapidly covered with a salivary protein pellicle to which bacteria bind, initiating biofilm formation. In this study, adherence of early colonizing streptococci, Streptococcus gordonii, Streptococcus oralis, Streptococcus mitis and Streptococcus sanguinis to two saliva-coated anodically oxidized surfaces was compared with that on commercially pure titanium (CpTi). Near edge X-ray absorption (NEXAFS) showed crystalline anatase was more pronounced on the anodically oxidized surfaces than on the CpTi. As revealed by fluorescence microscopy, a four-species mixture, as well as individual bacterial species, exhibited lower adherence after 2 h to the saliva-coated, anatase-rich surfaces than to CpTi. Since wettability did not differ between the saliva-coated surfaces, differences in the concentration and/or configuration of salivary proteins on the anatase-rich surfaces may explain the reduced bacterial binding effect. Anatase-rich surfaces could thus contribute to reduced overall biofilm formation on dental implant abutments through diminished adherence of early colonizers.
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| 16. |
- Ederth, Thomas, et al.
(författare)
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Anomalous settlement behavior of Ulva linza zoospores on cationic oligopeptide surfaces
- 2008
-
Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 24:4, s. 303-312
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Tidskriftsartikel (refereegranskat)abstract
- Identification of settlement cues for marine fouling organisms opens up new strategies and methods for biofouling prevention, and enables the development of more effective antifouling materials. To this end, the settlement behaviour of zoospores of the green alga Ulva linza onto cationic oligopeptide self-assembled monolayers (SAMs) has been investigated. The spores interact strongly with lysine- and arginine-rich SAMs, and their settlement appears to be stimulated by these surfaces. Of particular interest is an arginine-rich oligopeptide, which is effective in attracting spores to the surface, but in a way which leaves a large fraction of the settled spores attached to the surface in an anomalous fashion. These 'pseudo-settled' spores are relatively easily detached from the surface and do not undergo the full range of cellular responses associated with normal commitment to settlement. This is a hitherto undocumented mode of settlement, and surface dilution of the arginine-rich peptide with a neutral triglycine peptide demonstrates that both normal and anomalous settlement is proportional to the surface density of the arginine-rich peptide. The settlement experiments are complemented with physical studies of the oligopeptide SAMs, before and after extended immersion in artificial seawater, using infrared spectroscopy, null ellipsometry and contact angle measurements.
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| 17. |
- Granhag, Lena, 1974, et al.
(författare)
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Roughness-dependent removal of settled spores of the green alga Ulva (syn. Enteromorpha) exposed to hydrodynamic forces from a water jet
- 2004
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 20:2, s. 117-122
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Tidskriftsartikel (refereegranskat)abstract
- Topographic features change the hydrodynamic regime over surfaces subjected to flow. Hydrodynamic microenvironments around topographic structures may have consequences for recruitment and removal of propagules of marine benthic organisms. The settlement and adhesion of zoospores from the green alga Ulva linza (syn. Enteromorpha linza) to defined topographies was investigated. A range of topographic size scales (R-z: 25-100 mum) was manufactured from plankton nets, creating patterns with ridges and depressions. The topographic scales span a roughness similar to that of natural substrata and antifouling coatings. Spores were removed from the surfaces by a calibrated water jet. Fewer spores were removed from the smallest topographic structure tested (R-z: 25 mum) compared to both the smooth (R-z: 1) and the roughest (R-z: 100 mum) structures. Zoospores that settled in depressions were less likely to be removed compared to spores on the ridges. The results in terms of the interaction between surface topography and hydrodynamic forces have implications for both natural substrata exposed to wave action and antifouling surfaces on ships' hulls. The possible effects of topography on increasing zoospore adhesion and offering a refuge from hydrodynamic forces are discussed.
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| 18. |
- Hahn Berg, Cecilia I, et al.
(författare)
-
Intraoral Lubrication of PRP-1, Statherin and Mucin as Studied by AFM
- 2004
-
Ingår i: Biofouling (Print). - : Taylor & Francis. - 0892-7014 .- 1029-2454. ; 20:1, s. 65-70
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper was to elucidate the mechanisms behind salivary lubrication with special emphasis on the lubricity of three key components of the pellicle, viz human acidic proline-rich protein 1 (PRP-1), human statherin and bovine submaxillary mucin (BSM). The lubricating properties of the proteins have been assessed by means of colloidal probe atomic force microscopy, and are discussed in relation to their adsorption behaviour. To various extents, the proteins investigated all showed a lubricating effect when adsorbed to silica surfaces. For comparable concentrations, PRP-1 was found to have a more pronounced lubricating effect than BSM, which in turn showed a higher lubricity than statherin. The relative lubricity is in accordance with previously reported relative adsorbed amounts of the three proteins, within the investigated concentration interval. It is concluded that PRP-1 has the highest lubricating capacity as a pure fraction among the preparations investigated, and that the lubricating effect of PRP-1 as a pure fraction is notably large as compared to the lubricity of human whole saliva.
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| 19. |
- Hahn Berg, IC, et al.
(författare)
-
Intraoral lubrication of PRP-1, statherin and mucin as studied by AFM
- 2004
-
Ingår i: Biofouling (Print). - 0892-7014 .- 1029-2454. ; 20, s. 65-70
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper was to elucidate the mechanisms behind salivary lubrication with special emphasis on the lubricity of three pellicle key components (human acidic proline-rich protein 1 (PRP-1), human statherin and bovine submaxillary mucin (BSM)). The lubricating properties of the proteins have been assessed by means of colloidal probe atomic force microscopy, and are discussed in relation to their adsorption behavior. To various extent, the investigated proteins all showed a lubricating effect when adsorbed to silica surfaces. For comparable concentrations, PRP-1 was found to have a more pronounced lubricating effect than BSM, which in turn showed a higher lubricity than statherin. The relative lubricity is in accordance with previously reported relative adsorbed amounts of the three proteins, within the investigated concentration interval. We conclude that PRP-1 has the highest lubricating capacity as a pure fraction among the investigated preparations, and that the lubricating effect of PRP-1 as a pure fraction is notably large as compared to the lubricity of human whole saliva
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| 20. |
- Hahn Berg, IC, et al.
(författare)
-
Lubricating properties of the initial salivary pellicle – an AFM study
- 2003
-
Ingår i: Biofouling (Print). - 0892-7014 .- 1029-2454. ; 19, s. 365-369
-
Tidskriftsartikel (refereegranskat)abstract
- The role of saliva in the oral cavity is manifold; an important function is to serve as lubricant between hard (enamel) and soft (mucosal) tissues. Intraoral lubrication is of crucial importance in order to maintain functions such as deglutition, mastication and the faculty of speech. A large number of people suffer from impaired salivary functions, displaying symptoms such as 'dry mouth'. This results in a need for methods to assess the lubricating properties of both native saliva as well as potential artificial saliva formulations. Here we measure normal as well as lateral forces, acting between adsorbed salivary films, for the first time by means of colloidal probe atomic force microscopy. We find that the presence of salivary pellicles between hard surfaces reduces the friction coefficient by a factor of 20. This reduction of friction is consistent with the long-range purely repulsive nature of the normal forces acting between the salivary films. The lubricating mechanism is presumably based on a full separation of the sliding surfaces by the salivary films. The friction between salivary films has been investigated at normal loads that well cover the clinical jaw closing forces, and it can be concluded that the lubricating properties are maintained within this load interval. The present study indicates the usefulness of colloidal probe atomic force microscopy, which offers a direct and quantitative measure of the lubrication on a molecular level, in the study of biotribological phenomena. In particular, the results obtained here may have implications for the development of saliva substitutes
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| 21. |
- Hahn Berg, IC, et al.
(författare)
-
Salivary protein adsorption onto hydroxyapatite and SDS-mediated elution studied by in situ ellipsometry
- 2001
-
Ingår i: Biofouling (Print). - 0892-7014 .- 1029-2454. ; 17, s. 173-187
-
Tidskriftsartikel (refereegranskat)abstract
- Whole unstimulated saliva from two donors was investigated both with respect to adsorption characteristics and SDS-induced elutability. Salivary protein adsorption onto hydroxyapatite (HA) discs was studied by means of in situ ellipsometry in the concentration range 0.1-20% saliva. The adsorbed amounts on HA were found to be similar to those on silica, but the rates of adsorption were lower. Protein adsorption was virtually unaffected by the presence of Na+, whereas Ca2+ induced nucleation of calcium phosphate at the surface, the deposition rate being influenced by the pellicle age but not by the presence of saliva in bulk solution. The SDS elutability of adsorbed pellicles was determined on HA as well as on silica surfaces. Desorption from both surfaces was found to occur in the same SDS concentration range, although a residual layer was observed on HA. The slight net positive charge and lower charge density of HA as compared to the strongly negatively charged silica, may, at least partly, account for this observation by causing a reduction in the repulsive force between protein-surfactant complexes and the surface. Interindividual differences, observed in the adsorption as well as elution experiments, are thought to relate to the compositional differences observed by SDS-PAGE
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| 22. |
- Hamit-Eminovski, Jildiz, et al.
(författare)
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An ellipsometry study on the effect of aluminium chloride and ferric chloride formulations on mucin layers adsorbed at hydrophobic surfaces
- 2010
-
Ingår i: Biofouling (Print). - : Taylor & Francis. - 0892-7014 .- 1029-2454. ; 26:5, s. 511-518
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Tidskriftsartikel (refereegranskat)abstract
- Ellipsometry was used to investigate the effect of polyaluminium chloride (PAC) formulations of different degrees of hydrolysation on an adsorbed mucin film. The results were compared to the effect of aluminium chloride (AlCl3) and ferric chloride. A compaction of the mucin film took place upon addition of the formulations and this occurred to different extents and at different concentrations for the different formulations. The compaction of PAC of a low degree of hydrolysis behaved similarly to AlCl3. PAC of a high degree of hydrolysis showed a greater compaction effect than the other aluminium formulations. The initial compaction concentration was found to be 0.001 mM which is less than previously found for aluminium–mucin complex formation in bulk. The reversibility of the compaction was also investigated. The compaction of the mucin film was found to be partly reversible for AlCl3 and PAC of low degree of hydrolysis. No reversibility was observed for the formulations of PAC of high hydrolysis grade or for ferric chloride. The results are consistent with previously observed effects of PAC of a low degree of hydrolysis on bacterial surfaces where a compaction of surface polymers was indicated by the reduced range of repulsive steric interactions.
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| 23. |
- Hamit, Jildiz, et al.
(författare)
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Change in surface properties of Microthrix parvicella upon addition of polyaluminium chloride as characterized by atomic force microscopy
- 2010
-
Ingår i: Biofouling (Print). - : Taylor & Francis. - 0892-7014 .- 1029-2454. ; 26:3, s. 323-331
-
Tidskriftsartikel (refereegranskat)abstract
- The filamentous bacterium Microthrix parvicella causes severe separation and foaming problems at wastewater treatment plants (WWTPs). An effective control of the bacterium in activated sludge WWTPs can be accomplished by dosage with polyaluminium chloride (PAX-14). The purpose of this study was to investigate whether addition of PAX-14 affects surface properties such as the hydrophobicity of the bacterium and to study the exopolymers of M. parvicella that host surface-associated enzymes. To this end, force measurements by atomic force microscopy were carried out to measure the interactions between hydrophilic and hydrophobized tips and the bacterium surface. Addition of PAX-14 caused no changes in the hydrophobicity of the bacterium surface but the data indicate that it collapsed the polymeric layer likely due to electrostatic screening. It is concluded that the collapse of the polymeric layer may affect the transport of substrates (eg free fatty acids) to the bacterium and hence the competitiveness of M. parvicella compared to the other bacteria present in activated sludge.
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| 24. |
- Head, R. M., et al.
(författare)
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Gregarious settlement in cypris larvae: The effects of cyprid age and assay duration
- 2004
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 20:2, s. 123-128
-
Tidskriftsartikel (refereegranskat)abstract
- Gregarious behaviour of marine larvae is perhaps most clearly associated with finding a suitable habitat in a changeable or restricted environment, or with finding other conspecifics with which to mate. Prior work has shown that in settlement assays using cypris larvae of the barnacle Balanus amphitrite , gregarious interactions significantly affected the interpretation of experiments testing the activity of organic settlement promoters and inhibitors. Other studies have also shown effects of cyprid age and pheromone concentration on settlement behaviour. However, the effects of interactions between gregariousness and these two factors are not known. The aim of this study was to test the hypotheses that i) as cyprids age the effects of gregariousness become less apparent, and ii) as the duration of the experiment increases gregarious effects become more apparent, using cypris larvae of B. amphitrite and Balanus improvisus . Three age classes of cyprids were used at six densities in a fully factorial design. For B. improvisus cyprids significant gregarious effects occurred between 3 or more larvae, and although larval age and experiment duration had significant main effects, there were no interactions between these important factors and gregariousness. For B. amphitrite cyprids significant gregarious effects also occurred with greater than or equal to3 larvae per well, though this effect was strongly dependent upon experiment duration. B. amphitrite cyprid sensitivity to conspecific cues does not change with age, although increasing experiment duration and age interact to increase settlement. Differences between species may be due to different thresholds to conspecific larval cues, or B. improvisus cyprids release much more larval temporary adhesive during exploration.
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| 25. |
- Husmark, U., et al.
(författare)
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Bacillus spores and moulding with TTC agar: A useful method for the assessment of food processing equipment cleanability
- 1999
-
Ingår i: Biofouling (Print). - 0892-7014 .- 1029-2454. ; 14:1, s. 15-24
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work a powerful and practical method for the assessment of food processing equipment cleanability is described. Surfaces were soiled with Bacillus spores. After cleaning, surfaces were overlaid with agar containing a tetrazolium salt (TTC) which stained the growing colonies red. Stained colonies could be readily detected and counted. The poorer hygienically designed areas were easily observed and contamination levels could be defined. The TTC method was compared to other classical techniques such as contact plates, direct epifluorescence microscopy (DEM) and Shapton and Hindes (SH) agar. Recovery of bacteria using the TTC method was found to be a good complement to DEM and more accurate than contact plates and SH agar. Cleanability tests on closed equipment are also reported showing the utility of the TTC method.
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| 26. |
- Karacic, Sabina, 1987, et al.
(författare)
-
Subsea tunnel reinforced sprayed concrete subjected to deterioration harbours distinct microbial communities
- 2018
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 34:10, s. 1161-1174
-
Tidskriftsartikel (refereegranskat)abstract
- Deterioration of concrete is a large societal cost. In the Oslofjord subsea tunnel (Norway), deterioration of sprayed concrete and corrosion of reinforcing steel fibres occur under biofilm formed at sites with intrusion of saline groundwater. In this study, the microbial community structure, in situ environmental gradients and chemical composition of the biofilms were examined at three tunnel sites. Ammonia- and nitrite-oxidising microorganisms, in particular Nitrosopumilus sp., and iron-oxidising bacteria within Mariprofundus sp., were omnipresent, together with a diversity of presumably heterotrophic bacteria. Alpha- and beta diversity measures showed significant differences in richness and community structure between the sites as well as over time and null-models suggested that deterministic factors were important for the community assembly. The superficial flow of water over the biofilm had a strong effect on oxygen penetration in the biofilm and was identified as one major environmental gradient that varied between the sites, likely being important for shaping the microbial communities. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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| 27. |
- Kaur, Simarpreet Pal, et al.
(författare)
-
Unhindered copper uptake by glutaraldehyde-polyethyleneimine coatings in an artificial seawater model system with adsorbed swollen polysaccharides and competing ligand EDTA
- 2017
-
Ingår i: Biofouling (Print). - : Taylor and Francis Ltd.. - 0892-7014 .- 1029-2454. ; 33:2, s. 184-194
-
Tidskriftsartikel (refereegranskat)abstract
- Shortly after a surface is submerged in the sea, a conditioning film is generally formed by adsorption of organic molecules, such as polysaccharides. This could affect transport of molecules and ions between the seawater and the surface. An artificial seawater model system was developed to understand how adsorbed polysaccharides impact copper binding by glutaraldehyde-crosslinked polyethyleneimine coatings. Coating performance was also determined when competed against copper-chelating EDTA. Polysaccharide adsorption and copper binding and distribution were investigated using advanced analytical techniques, including depth-resolved time-of-flight secondary ion mass spectroscopy, grazing incidence X-ray absorption near-edge spectroscopy, quartz crystal microbalance with dissipation monitoring and X-ray photoelectron spectroscopy. In artificial seawater, the polysaccharides adsorbed in a swollen state that copper readily penetrated and the glutaraldehyde-polyethyleneimine coatings outcompeted EDTA for copper binding. Furthermore, the depth distribution of copper species was determined with nanometre precision. The results are highly relevant for copper-binding and copper-releasing materials in seawater.
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| 28. |
- Lindgren, Fredrik, 1979, et al.
(författare)
-
Copper release rate needed to inhibit fouling on the west coast of Sweden and control of copper release using zinc oxide
- 2018
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 34:4, s. 453-463
-
Tidskriftsartikel (refereegranskat)abstract
- How zinc oxide influences copper release has been tested and the lowest release rate of copper from various combinations of copper and zinc in a paint matrix evaluated, whilst still deterring macrofouling, including barnacles and bryozoans. Copper (I) oxide was added to a generic AF paint in 0, 8.5, 11.7 or 16.3 wt% copper oxide in combination with 0, 10 or 20 wt% zinc oxide and applied on PMMA panels. The results show that zinc influences the release rate of copper. When 10 and 20 wt% zinc was added, the total amount of copper released significantly increased by on average 32 and 47% respectively. All treatments that included copper were successful in deterring macrofouling, including the treatment with the lowest average Cu release rate, ie 4.68gcm(-2)day(-1).
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| 29. |
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| 30. |
- Lindh, Liselott, et al.
(författare)
-
An in vitro study of initial adsorption from human parotid and submandibular/sublingual resting saliva at solid/liquid interfaces
- 2001
-
Ingår i: Biofouling (Print). - : Taylor and Francis. - 0892-7014 .- 1029-2454. ; 17:3, s. 227-239
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of saliva concentration, saliva total protein content and the wetting characteristics of exposed solids on in vitro film formation was studied by the technique of in situ ellipsometry. The rates and plateau values of adsorption (45 min) at solid/liquid interfaces (hydrophilic silica and hydrophobic methylated silica surfaces) were determinated for human parotid (HPS) and submandibular/sublingual (HSMSLS) resting saliva solutions (0.1 and 1.0%, (v/v), saliva in phosphate buffered saline). Adsorption rates were related to a model assuming mass transport through an unstirred layer adjacent to the surface. The results showed that the adsorption was rapid, concentration dependent and higher on hydrophobic than on hydrophilic surfaces. Analysis of the influence of protein concentration on the adsorbed amounts demonstrated an interaction between protein concentration and the two surfaces for HPS and HSMSLS, respectively. This may indicate differences in binding mode. Inter-individual differences were found not to be significant at the 1% level of probability. Comparison of the observed adsorption and calculated diffusion rates suggest that on hydrophilic surfaces initial adsorption of proteins diffusing at rates corresponding to those of statherin and aPRPs takes place, whereas on hydrophobic surfaces lower molecular mass compounds appear to be involved.
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| 31. |
- Lindh, Liselott, et al.
(författare)
-
Concentration dependence of adsorption from human whole resting saliva at solid/liquid interfaces : An ellipsometric study
- 1999
-
Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 14:3, s. 189-196
-
Tidskriftsartikel (refereegranskat)abstract
- The rates and plateau values of adsorption at the solid/ liquid interface from human whole resting saliva from three male donors were studied in vitro. The influence of saliva concentration, the total protein content and the wettability of the exposed solids was investigated. Ellipsometry was used to study the rate and plateau values of the adsorption process in situ. The solid surfaces used were hydrophilic, negatively charged, silica and hydrophobic methylated silica. Salivary films were formed by adsorption from solutions of 0.05%, 0.10%, 0.20%, 0.50%, 1.0% and 2.0% (v/v) saliva in phosphate buffered saline. The results revealed that adsorption onto both types of surfaces was a rapid and, as expected, a concentration dependent process. The adsorbed amounts were in the range of monomolecular layers and were found to be larger onto the hydrophobic than the hydrophilic surfaces (p≤0.0062). A strong concentration dependence was denoted in all cases (p< 0.0001). Inter-individual differences were found not to be significant (0.0636 ≤ p≤ 0.8508) at any of the saliva concentrations. However, an interaction was shown (p < 0.0001) between the protein concentrations and the donors, indicating qualitative differences in protein content and surface activity.
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| 32. |
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| 33. |
- Lindh, Liselott, et al.
(författare)
-
On the adsorption of human proline-rich proteins (PRP-1 and PRP-3) and statherin at solid/liquid interfaces
- 2002
-
Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 18:2, s. 87-94
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of the present study was to investigate the adsorption of PRP-1, PRP-3 and statherin to solid surfaces in terms of dependence on concentration, the presence of electrolyte and surface wettability. Time resolved in situ ellipsometry was used to determine the adsorbed amounts and adsorption rates of pure PRP-1, PRP-3 and statherin onto pure (hydrophilic) and methylated (hydrophobized) silica surfaces. The initial film build-up was fast and plateaus were reached within 10 min at all concentrations for both types of surfaces and all proteins. The observed adsorption and calculated diffusion rates of PRP-1, PRP-3 and statherin, respectively, indicated that the initial adsorption was mass transport controlled at low concentrations. At hydrophobic surfaces, isotherm shapes and adsorbed amounts were similar for PRP-1 and PRP-3, while statherin adsorbed to a higher extent. At hydrophilic surfaces only PRP-1 adsorbed substantially, while for PRP-3 and statherin adsorbed amounts were low. The presence of Ca 2+ ions in the phosphate buffer solution increased the adsorption of statherin and PRP-3 on hydrophobic surfaces, while PRP-1 was unaffected. On hydrophilic surfaces, all three proteins adsorbed in higher amounts in NaCl, compared to CaCl 2 at similar ionic strength. It is concluded that acidic PRPs (PRP-1 and PRP-3) and statherin readily form films on a variety of materials and solution conditions, showing that their functions may be fulfilled under a wide range of conditions.
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| 34. |
- Marty, Florence, et al.
(författare)
-
Identification of key factors in Accelerated Low Water Corrosion through experimental simulation of tidal conditions : Influence of stimulated indigenous microbiota
- 2014
-
Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 30:3, s. 281-297
-
Tidskriftsartikel (refereegranskat)abstract
- Biotic and abiotic factors favoring Accelerated Low Water Corrosion (ALWC) on harbor steel structures remain unclear warranting their study under controlled experimental tidal conditions. Initial stimulation of marine microbial consortia by a pulse of organic matter resulted in localized corrosion and the highest corrosion rates (up to 12-times higher than non-stimulated conditions) in the low water zone, persisting after nine months exposure to natural seawater. Correlations between corrosion severity and the abundance and composition of metabolically active sulfate-reducing bacteria (SRB) indicated the importance and persistence of specific bacterial populations in accelerated corrosion. One phylotype related to the electrogenic SRB Desulfopila corrodens appeared as the major causative agent of the accelerated corrosion. The similarity of bacterial populations related to sulfur and iron cycles, mineral and tuberculation with those identified in ALWC support the relevance of experimental simulation of tidal conditions in the management of steel corrosion exposed to harbor environments.
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| 35. |
- Nugraha, Roni, et al.
(författare)
-
Antifouling properties of oligo(lactose)-based self-assembled monolayers
- 2015
-
Ingår i: Biofouling (Print). - : Taylor andamp; Francis: STM, Behavioural Science and Public Health Titles. - 0892-7014 .- 1029-2454. ; 31:1, s. 123-134
-
Tidskriftsartikel (refereegranskat)abstract
- The antifouling (AF) properties of oligo(lactose)-based self-assembled monolayers (SAMs), using four different proteins, zoospores of the green alga Ulva linza and cells of the diatom Navicula incerta, were investigated. The SAM-forming alkylthiols, which contained 1, 2 or 3 lactose units, showed significant variation in AF properties, with no differences in wettability. Non-specific adsorption of albumin and pepsin was low on all surfaces. Adsorption of lysozyme and fibrinogen decreased with increasing number of lactose units in the SAM, in agreement with the generally observed phenomenon that thicker hydrated layers provide higher barriers to protein adsorption. Settlement of spores of U. linza followed an opposite trend, being greater on the bulkier, more hydrated SAMs. These SAMs are more ordered for the larger saccharide units, and it is therefore hypothesized that the degree of order, and differences in crystallinity or stiffness between the surfaces, is an important parameter regulating spore settlement on these surfaces.
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| 36. |
- Ohlauson, Cecilia, et al.
(författare)
-
A comparison of toxicant-induced succession for five antifouling compounds on marine periphyton in SWIFT microcosms
- 2014
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 30:1, s. 41-50
-
Tidskriftsartikel (refereegranskat)abstract
- Five antifouling biocides, chlorothalonile, dichlofluanide, medetomidine, tolylfluanide, and zinc pyrithione, were evaluated regarding their effect on the composition of the periphyton community and the subsequent toxicant-induced succession (TIS). The periphyton communities were exposed in a semi-static setting for 96 h using a SWIFT microcosm. As a measure of community composition, pigment profiles from the exposed communities were used as effect indicators and compared with unexposed parts of the same community using the Bray-Curtis dissimilarity index. Chlorothalonile caused changes in the community starting at 85 μg l-1 while dichlofluanide had no effect even at the highest concentrations used, 810 μg l-1. The related substance tolylfluanide only affected the community composition at 2700 μg l-1. Medetomidine had a different response curve with a small effect on the community composition at 0.8 μg l-1 which then disappeared only to reappear at 240 μg l-1. Zinc pyrithione had the largest effect on the periphyton community with changes starting at 10 μg l-1 and no detectable pigments at 100 μg l-1. The changes in the community composition for the five substances were also compared using multidimensional scaling. When all substances were analyzed and plotted together, chlorothalonile, dichlofluanide, medetomidine, and tolylfluanide showed surprisingly similar effects compared to zinc pyrithione that gave very different TIS. However, when only chlorothalonile, dichlofluanide, and tolylfluanide were plotted together, clear differences in TIS between the three toxicants were revealed. Dichlofluanide only induced small effects, while concentration-dependent TIS trajectories for chlorothalonile and tolylfluanide took off in opposite directions indicating very different responses of the periphyton communities. This study demonstrates that substances with a similar chemical structure and mechanisms of action can have different effects on the community composition. With the exception of zinc pyrithione, none of the recorded effect levels were at concentrations reported from marine environments so far. © 2013 © 2013 Taylor & Francis.
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| 37. |
- Ohlauson, Cecilia, et al.
(författare)
-
Short-term effects of medetomidine on photosynthesis and protein synthesis in periphyton, epipsammon and plankton communities in relation to predicted environmental concentrations
- 2012
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 28:5, s. 491-499
-
Tidskriftsartikel (refereegranskat)abstract
- Medetomidine is a new antifouling substance, highly effective against barnacles. As part of a thorough ecotoxicological evaluation of medetomidine, its short-term effects on algal and bacterial communities were investigated and environmental concentrations were predicted with the MAMPEC model. Photosynthesis and bacterial protein synthesis for three marine communities, viz. periphyton, epipsammon and plankton were used as effect indicators, and compared with the predicted environmental concentrations (PECs). The plankton community showed a significant decrease in photosynthetic activity of 16% at 2 mg l(-1) of medetomidine, which was the only significant effect observed. PECs were estimated for a harbor, shipping lane and marina environment using three different model scenarios (MAMPEC default, Baltic and OECD scenarios). The highest PEC of 57 ng l(-1), generated for a marina with the Baltic scenario, was at least 10,000-fold lower than the concentration that significantly decreased photosynthetic activity. It is concluded that medetomidine does not cause any acute toxic effects on bacterial protein synthesis and only small acute effects on photosynthesis at high concentrations in marine microbial communities. It is also concluded that the hazard from medetomidine on these processes is low since the effect levels are much lower than the highest PEC.
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| 38. |
- Oliveira, Dinis, 1991, et al.
(författare)
-
Effect of ship hull form on the resistance penalty from biofouling
- 2018
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 34, s. 262-272
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Hull biofouling is a well-known problem for the shipping industry, leading to increased resistance and fuel consumption. Considering that the effects of hull form on resistance are known to be higher for a less slender hull, it is hypothesised in this paper that the effect of biofouling roughness on resistance is also dependent on the hull form. To test this hypothesis, previously reported full-scale numerical results on a containership are re-analysed. Form effects on roughness penalties, corresponding to K ΔCT =0.058±0.025, are observed at a low speed (19 knots, Re s =2.29×10 9 ), which are however cancelled out by traditionally neglected roughness effects on wave-making resistance at a higher speed (24 knots, Re s =2.89×10 9 ). It is concluded that hull form effects on biofouling penalties can be significant at low speeds, though not generalisable for higher speeds, namely when wave-making resistance corresponds to≥29% of total resistance.
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| 39. |
- Oliveira, Dinis, 1991, et al.
(författare)
-
Ship hull in-water cleaning and its effects on fouling-control coatings
- 2020
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 36:3, s. 332-350
-
Tidskriftsartikel (refereegranskat)abstract
- Today, ship hull fouling is managed through fouling-control coatings, complemented with inwater cleaning. During cleaning, coating damage and wear must be avoided, for maximum coating lifetime and reduced antifoulant release. When possible, cleaning should target early stages of fouling, using minimal forces. However, such forces, and their effects on coatings, have not yet been fully quantified. In this one-year study, minimal cleaning forces were determined using a newly-designed immersed waterjet. The results show that bi-monthly/monthly cleaning, with maximum wall shear stress up to 1.3 kPa and jet stagnation pressure 0.17 MPa, did not appear to cause damage or wear on either the biocidal antifouling (AF) or the biocide-free foul-release (FR) coatings. The AF coating required bi-monthly cleanings to keep fouling to incipient slime (time-averaged results), while the FR coating had a similar fouling level even without cleaning. The reported forces may be used in matching cleaning parameters to the adhesion strength of the early stages of fouling.
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| 40. |
- Oliveira, Dinis, 1991, et al.
(författare)
-
Towards an absolute scale for adhesion strength of ship hull microfouling
- 2019
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 35:2, s. 244-258
-
Tidskriftsartikel (refereegranskat)abstract
- In-water ship hull cleaning enables significant fuel savings through removal of marine fouling from underwater surfaces. Unfortunately, cleaning may also shorten the lifetime of hull coatings, with subsequent increase in fouling growth rate. Deleterious effects of cleaning would be minimized by matching cleaning forces to the adhesion strength of early stages of fouling, or microfouling. Calibrated waterjets are routinely used for comparing different coatings in terms of adhesion strength of microfouling. However, an absolute scale is lacking for translating such results into cleaning forces, of interest for design and operation of hull cleaning devices. This paper discusses how to determine such forces, namely using Computational Fluid Dynamics. Semi-empirical formulas are derived for forces under immersed waterjets, where the normal and tangential components of wall forces are given as functions of different flow parameters. Nozzle translation speed is identified as a parameter for future research, as this may affect cleaning efficacy.
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| 41. |
- Pansch, Christian, et al.
(författare)
-
A new flow-through bioassay for testing low-emission antifouling coatings
- 2017
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 33:8, s. 613-623
-
Tidskriftsartikel (refereegranskat)abstract
- Current antifouling (AF) technologies are based on the continuous release of biocides into the water, and consequently discharge into the environment. Major efforts to develop more environmentally friendly coatings require efficient testing in laboratory assays, followed by field studies. Barnacles are important fouling organisms worldwide, increasing hydrodynamic drag on ships and damaging coatings on underwater surfaces, and thus are extensively used as models in AF research, mostly in static, laboratory-based systems. Reliable flow-through test assays for the screening of biocidecontaining AF paints, however, are rare. Herein, a flow-through bioassay was developed to screen for diverse low-release biocide paints, and to evaluate their effects on pre- andpost-settlement traits in barnacles. The assay distinguishes between the effects from direct surface contact and bulk-water effects, which are crucial when developing low-emission AF coatings. This flow-through bioassay adds a new tool for rapid laboratory-based first-stage screening of candidate compounds and novel AF formulations.
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| 42. |
- Persson, Frank, 1970, et al.
(författare)
-
Ecological role of a seaweed secondary metabolite for a colonizing bacterial community
- 2011
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 27:6, s. 579-588
-
Tidskriftsartikel (refereegranskat)abstract
- Bacteria associated with seaweeds can both harm and benefit their hosts. Many seaweed species are known to produce compounds that inhibit growth of bacterial isolates, but the ecological role of seaweed metabolites for the associated bacterial community structure is not well understood. In this study the response of a colonizing bacterial community to the secondary metabolite (1,1,3,3-tetrabromo-2-heptanone) from the red alga Bonnemaisonia hamifera was investigated by using field panels coated with the metabolite at a range of concentrations covering those measured at the algal surface. The seaweed metabolite has previously been shown to have antibacterial effects. The metabolite significantly affected the natural fouling community by (i) altering the composition, (ii) altering the diversity by increasing the evenness and (iii) decreasing the density, as measured by terminal restriction fragment length polymorphism in conjunction with clone libraries of the 16S rRNA genes and by bacterial enumeration. No single major bacterial taxon (phylum, class) was particularly affected by the metabolite. Instead changes in community composition were observed at a more detailed phylogenetic level. This indicates a broad specificity of the seaweed metabolite against bacterial colonization, which is supported by the observation that the bacterial density was significantly affected at a lower concentration (0.02 μg cm -2) than the composition (1-2.5 μg cm -2) and the evenness (5 μg cm -2) of the bacterial communities. Altogether, the results emphasize the role of secondary metabolites for control of the density and structure of seaweed-associated bacterial communities.
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| 43. |
- Petrone, Luigi, et al.
(författare)
-
Effects of surface charge and Gibbs surface energy on the settlement behaviour of barnacle cyprids (Balanus amphitrite)
- 2011
-
Ingår i: Biofouling (Print). - : Taylor and Francis: STM, Behavioural Science and Public Health Titles / Taylor and Francis. - 0892-7014 .- 1029-2454. ; 27:9, s. 1043-1055
-
Tidskriftsartikel (refereegranskat)abstract
- Gibbs surface energy has long been considered to be an important parameter in the design of fouling-resistant surfaces for marine applications. Rigorous testing of the hypothesis that settlement is related to Gibbs surface energy however has never been accomplished, due mainly to practical limitations imposed by the necessary combination of surface engineering and biological evaluation methods. In this article, the effects of surface charge and Gibbs surface energy on the settlement of cyprids of an important fouling barnacle, Balanus amphitrite, were evaluated. Settlement assays were conducted on a range of self-assembled monolayers (SAMs) (CH(3)-, OH-, COOH-, N(CH(3))(3)(+)-, NH(2)-terminated), presented in gold-coated polystyrene well plates, varying in terms of their surface charge and Gibbs surface energy. Contrary to contemporary theory, settlement was not increased by high-energy surfaces, rather the opposite was found to be the case with cyprids settling in greater numbers on a low-energy CH(3)- SAM compared to a high-energy OH- SAM. Settlement was also greater on negatively-charged SAMs, compared to neutral and positively-charged SAMs. These findings are discussed in the context of data drawn from surfaces that varied in multiple characteristics simultaneously, as have been used previously for such experiments. The finding that surface charge, rather than total surface energy, may be responsible for surface selection by cyprids, will have significant implications for the design of future fouling-resistant materials.
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| 44. |
- Pinori, Emiliano, et al.
(författare)
-
Multi-seasonal barnacle (Balanus improvisus) protection achieved by trace amounts of a macrocyclic lactone (ivermectin) included in rosin-based coatings.
- 2011
-
Ingår i: Biofouling. - : Informa UK Limited. - 1029-2454 .- 0892-7014. ; 27:9, s. 941-53
-
Tidskriftsartikel (refereegranskat)abstract
- Rosin-based coatings loaded with 0.1% (w/v) ivermectin were found to be effective in preventing colonization by barnacles (Balanus improvisus) both on test panels as well as on yachts for at least two fouling seasons. The leaching rate of ivermectin was determined by mass-spectroscopy (LC/MS-MS) to be 0.7ng cm(-2) day(-1). This low leaching rate, as deduced from the Higuchi model, is a result of the low loading, low water solubility, high affinity to the matrix and high molar volume of the model biocide. Comparison of ivermectin and control areas of panels immersed in the field showed undisturbed colonisation of barnacles after immersion for 35 days. After 73 days the mean barnacle base plate area on the controls was 13mm(2), while on the ivermectin coating it was 3mm(2). After 388 days, no barnacles were observed on the ivermectin coating while the barnacles on the control coating had reached a mean of 60mm(2). In another series of coated panels, ivermectin was dissolved in a cosolvent mixture of propylene glycol and glycerol formal prior to the addition to the paint base. This method further improved the anti-barnacle performance of the coatings. An increased release rate (3ng cm(-2) day(-1)) and dispersion of ivermectin, determined by fluorescence microscopy, and decreased hardness of the coatings were the consequences of the cosolvent mixture in the paint. The antifouling mechanism of macrocyclic lactones, such as avermectins, needs to be clarified in further studies. Beside chronic intoxication as ivermectin is slowly released from the paint film even contact intoxication occurring inside the coatings, triggered by penetration of the coating by barnacles, is a possible explanation for the mode of action and this is under investigation.
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| 45. |
- Pinori, Emiliano, et al.
(författare)
-
The impact of coating hardness on the anti-barnacle efficacy of an embedded antifouling biocide
- 2013
-
Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 29:7, s. 763-773
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy of antifouling coatings designed to minimise the release of biocide, either by embedded (non-covalent) or tethered (covalently bonded) biocides, relies on sufficient bioavailability of the active compound upon contact between the organism and the coating. This investigation is focused on whether coating hardness affects the efficacy of embedded coating systems. Two experimental, non-eroding and waterborne latex paint formulations composed mainly of polystyrene (PS) or polyvinyl versatate (PV) were chosen for their difference in mechanical properties measured in terms of Buchholz indentation resistance. Ivermectin was added to both formulations to a final concentration of 0.1% (w/v) and the steady state release rate was measured according to ISO 15181 at between 34 and 70ngcm(-2)day(-1) for both formulations. Field trials conducted over 3months showed significant differences in anti-barnacle efficacy between the formulations despite their similar release profiles. The softer PV coating showed complete anti-barnacle efficacy, ie no barnacles were detected, while the harder PS coating showed no efficacy against barnacle colonisation during the same time period. The results indicate a new antifouling strategy whereby a route of intoxication is triggered by the organism itself upon interaction with the coating and its embedded biocide. This finding opens new possibilities in controlling macrofouling by low emission antifouling coatings.
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| 46. |
- Santos, Olga, et al.
(författare)
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Adsorption from saliva to silica and hydroxyapatite surfaces and elution of salivary films by SDS and delmopinol
- 2010
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Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 26:6, s. 697-710
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of human whole saliva (HWS) onto silica and hydroxyapatite surfaces (HA) was followed by quartz crystal microbalance with dissipation (QCM-D) and ellipsometry. The influence of different surface properties and adsorption media (water and PBS) on the HWS adsorption was studied. The viscoelastic properties of the saliva films formed onto the solid surfaces were estimated by the use of the Voigt-based viscoelastic film model. Furthermore, the efficiency of SDS and delmopinol to elute the adsorbed saliva film from the surfaces was investigated at different surfactant concentrations. It was observed a biphasic kinetic regime for the adsorption of saliva on the silica and HA surfaces, indicating the formation of a rigidly coupled first layer corresponding to an initial adsorption of small proteins and a more loosely bound second layer. The results further showed a higher adsorption of HWS onto the HA surfaces compared to the silica surfaces in both adsorption media (PBS and water). The adsorption in PBS led to higher adsorbed amounts on both surfaces as compared to water. SDS was found to be more efficient in removing the saliva film from both surfaces than delmopinol. The salivary film was found to be less tightly bound on to the silica surfaces since more saliva film could be removed with both SDS and delmopinol compared to from the HA surface. When saliva was adsorbed from PBS a higher energy dissipation was determined implying that a softer saliva layer is build up in PBS as opposed to in water. In the same media (water) a softer saliva layer was formed onto the HA surfaces, while in PBS the saliva layer formed at both surfaces seems to have similar structure.
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| 47. |
- Santos, Olga, et al.
(författare)
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Adsorption of HSA, IgG and laminin-1 on model titania surfaces : effects of glow discharge treatment on competitively adsorbed film composition
- 2011
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Ingår i: Biofouling (Print). - : Taylor & Francis. - 0892-7014 .- 1029-2454. ; 27:9, s. 1003-1015
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effect of glow discharge treatment of titania surfaces on plasma protein adsorption, by means of ellipsometry and mechanically assisted SDS elution. The adsorption and film elution of three plasma proteins, viz. human serum albumin (HSA), human immunoglobulin G (IgG) and laminin-1, as well as competitive adsorption from a mixture of the three proteins, showed that the adsorbed amount of the individual proteins after 1 h increased in the order HSA
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| 48. |
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| 49. |
- Sjögren, M., et al.
(författare)
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Antifouling activity of the sponge metabolite agelasine D and synthesised analogs on Balanus improvisus
- 2008
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Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 24:4, s. 251-258
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Tidskriftsartikel (refereegranskat)abstract
- This study reports a screening study for antifouling (AF) activity of the natural compound agelasine D isolated from marine sponges of the genus Agelas and 20 synthesised analogs of agelasines and agelasimines. Agelasine D, together with two of the analogs, ie AV1003A and AKB695, displayed a strong inhibitory effect on settlement of Balanus improvisus cypris larvae. Agelasine D had an EC50 value of 0.11 mu M while the two analogs AV1033A and AKB695 had EC50 values of 0.23 and 0.3 mu M, respectively. None of these three compounds affected larval mortality as was the case with several of the analogs tested. Moreover, the effect of AV1033A and AKB695 was reversible. When cyprids after 24 h exposure to the compounds were transferred to fresh seawater, the settlement frequency compared with the controls was completely recovered. The properties of the agelasine D analogs AV1003A and AKB695 make them highly attractive candidates as AF agents in future marine coatings.
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| 50. |
- Sjögren, Martin, et al.
(författare)
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Recruitment in the field of Balanus improvisus and Mytilus edulis in response to the antifouling cyclopeptides barettin and 8,9-dihydrobarettin from the marine sponge Geodia barretti
- 2004
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Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 20:6, s. 291-297
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Tidskriftsartikel (refereegranskat)abstract
- In this field investigation the two cyclopeptides, isolated from the marine sponge Geodia barretti Bowerbank (Geodiidae, Astrophorida), are shown to be very efficient in preventing recruitment of the barnacle Balanus improvisus (Cirripedia, Crustacea) and the blue mussel Mytilis edulis (Protobranchia, Lamellibranchia) when included in different marine paints. These brominated cyclopeptides, named barettin and 8,9-dihydrobarettin were incorporated in different non-toxic coatings. The substances were used in the concentrations 0.1 and 0.01% in all treatments. The most efficient paint was a SPC polymer. This paint, in combination with barettin and 8,9-dihydrobarettin, reduced the recruitment of B. improvisus by 89% (barettin, 0.1%) and by 67% (8,9-dihydrobarettin, 0.1%) as compared to control panels. For M. edulis, the reduction of recruitment was 81% with barettin (0.1%) and 72% with 8,9-dihydrobarettin (0.1%) included in the SPC paint. This indicates that the two compounds from G. barretti could provide non-toxic alternatives as additives in antifouling paints, since the heavy metal-based marine paints are to be replaced.
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