This document summarizes research on reducing biofouling on horizontal axis tidal turbines through the use of engineered surface microstructures. It discusses existing anti-fouling methods and their limitations. Surface microtopographies found in nature, like shark skin and lotus leaves, show excellent anti-fouling properties and modern techniques allow for creating engineered microstructures. The document suggests that while microstructures may reduce biofouling, applying them to large tidal turbines is not currently financially viable due to the lack of an automated application process. Further research is needed to develop cost-effective methods for applying microstructures at large scales.
EFFECTS OF HEAVY METAL CONTAMINATION ON SOIL MICROBIALgudlord nkosi
This document summarizes a study on the effects of heavy metal contamination on soil microbial biomass. The study aimed to determine if heavy metal contamination affects soil microbial biomass. Soil and heavy metal samples were collected from a contaminated site and analyzed over 8 weeks. The results showed that bacteria levels initially increased with heavy metal exposure but then declined from week 4 to 8. Lead and arsenic had the highest negative impact on soil fungi levels. The conclusion is that added heavy metals change the soil microbial community structure and activities over time.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This document summarizes a research study on the prospects of using recycled coarse aggregate for concrete production in Nigeria. The study replaced the coarse aggregate component of normal concrete with 25%, 50%, 75% and 100% recycled coarse aggregate. Results showed that workability, density, compressive strength and flexural strength decreased with increased recycled coarse aggregate content. However, concrete with 100% recycled coarse aggregate met the minimum strength requirements for plain low-strength concrete elements without additives. The study recommends using recycled coarse aggregate concrete for plain, low-strength concrete building elements. This could help reuse demolished construction waste and reduce environmental and health risks from extracting new aggregates.
A Proposed Method for Safe Disposal of Consumed Photovoltaic ModulesIJERA Editor
The growth of domestic and large-scale applications of solar energy, especially photovoltaic (PV) cells which reaches annually up to 40 % worldwide since 2000, means that the technology has stepped out from demonstration phase to large-scale deployment. Several countries have started to exploit this huge potential as part of their future energy supply. Photovoltaic cells are manufactured from various semiconductors; materials that are moderately good conductors for electricity but harmful to the environment. End-of-life disposal of PV modules can be an environmental issue. However, due to the long lifespan of PV modules (25 to 30 years), currently most PV modules have not reached the disposal stage. As a result, there is very little experience and knowledge with the disposal and/or recycling techniques of PV modules. This paper proposes a method for safe disposal of solar panels after the end of their life by burying the PV cells into concrete blocks that may be used in different civil applications. Two types of PV cells (mono-crystalline & multi-crystalline) are selected to be mixed with concrete components to investigate their effect on properties of concrete. The experimental results showed that the PV cells have an effect on the concrete properties. Reduction of concrete compressive strength and density, while an increase in the concrete porosity were observed. In General, this study showed the validity of the proposed method to be further investigated for safe disposal of consumed photovoltaic modules
Concentration of metal pollutants in river kubanni, zaria, nigeria.Alexander Decker
The document analyzes metal pollutant concentration levels in River Kubanni in Zaria, Nigeria. Sediment samples were collected from four locations along the river and analyzed using Instrumental Neutron Activation Analysis. 29 metal pollutants were identified, including magnesium, aluminum, calcium, titanium, vanadium, manganese, and more. Concentration levels varied along the river's course and between pollutants. Most metal contaminants originated from anthropogenic activities in the catchment area, while some were from geological formations. The presence of many metals could negatively impact human health due to carcinogenic and bioaccumulative properties. Control of polluting activities in the catchment area was recommended.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Hydraulic Fracturing or ‘Fracking’: A Short Summary of Current Knowledge and ...Marcellus Drilling News
A small-scale study written by Dr. Dave Healy with the University of Aberdeen (Ireland), and released by the Irish Environmental Protection Agency. This 26-page "preliminary study" explores and summarizes current knowledge about the environmental considerations and impacts of shale gas exploration and extraction, and in particular the use of hydraulic fracturing technology.
This document provides an overview and introduction to a course on geotechnical engineering at Chinhoyi University of Technology. It covers topics like soil formation, properties of soils, soil classification, soil compaction and permeability. It discusses soil mechanics, different types of soils like residual and alluvial soils. It also explains concepts like weathering, clay mineralogy, basic structural units and types of clay minerals like kaolinite, montmorillonite and illite. The document is intended to help students understand the key principles and applications of soil mechanics in engineering.
EFFECTS OF HEAVY METAL CONTAMINATION ON SOIL MICROBIALgudlord nkosi
This document summarizes a study on the effects of heavy metal contamination on soil microbial biomass. The study aimed to determine if heavy metal contamination affects soil microbial biomass. Soil and heavy metal samples were collected from a contaminated site and analyzed over 8 weeks. The results showed that bacteria levels initially increased with heavy metal exposure but then declined from week 4 to 8. Lead and arsenic had the highest negative impact on soil fungi levels. The conclusion is that added heavy metals change the soil microbial community structure and activities over time.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This document summarizes a research study on the prospects of using recycled coarse aggregate for concrete production in Nigeria. The study replaced the coarse aggregate component of normal concrete with 25%, 50%, 75% and 100% recycled coarse aggregate. Results showed that workability, density, compressive strength and flexural strength decreased with increased recycled coarse aggregate content. However, concrete with 100% recycled coarse aggregate met the minimum strength requirements for plain low-strength concrete elements without additives. The study recommends using recycled coarse aggregate concrete for plain, low-strength concrete building elements. This could help reuse demolished construction waste and reduce environmental and health risks from extracting new aggregates.
A Proposed Method for Safe Disposal of Consumed Photovoltaic ModulesIJERA Editor
The growth of domestic and large-scale applications of solar energy, especially photovoltaic (PV) cells which reaches annually up to 40 % worldwide since 2000, means that the technology has stepped out from demonstration phase to large-scale deployment. Several countries have started to exploit this huge potential as part of their future energy supply. Photovoltaic cells are manufactured from various semiconductors; materials that are moderately good conductors for electricity but harmful to the environment. End-of-life disposal of PV modules can be an environmental issue. However, due to the long lifespan of PV modules (25 to 30 years), currently most PV modules have not reached the disposal stage. As a result, there is very little experience and knowledge with the disposal and/or recycling techniques of PV modules. This paper proposes a method for safe disposal of solar panels after the end of their life by burying the PV cells into concrete blocks that may be used in different civil applications. Two types of PV cells (mono-crystalline & multi-crystalline) are selected to be mixed with concrete components to investigate their effect on properties of concrete. The experimental results showed that the PV cells have an effect on the concrete properties. Reduction of concrete compressive strength and density, while an increase in the concrete porosity were observed. In General, this study showed the validity of the proposed method to be further investigated for safe disposal of consumed photovoltaic modules
Concentration of metal pollutants in river kubanni, zaria, nigeria.Alexander Decker
The document analyzes metal pollutant concentration levels in River Kubanni in Zaria, Nigeria. Sediment samples were collected from four locations along the river and analyzed using Instrumental Neutron Activation Analysis. 29 metal pollutants were identified, including magnesium, aluminum, calcium, titanium, vanadium, manganese, and more. Concentration levels varied along the river's course and between pollutants. Most metal contaminants originated from anthropogenic activities in the catchment area, while some were from geological formations. The presence of many metals could negatively impact human health due to carcinogenic and bioaccumulative properties. Control of polluting activities in the catchment area was recommended.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Hydraulic Fracturing or ‘Fracking’: A Short Summary of Current Knowledge and ...Marcellus Drilling News
A small-scale study written by Dr. Dave Healy with the University of Aberdeen (Ireland), and released by the Irish Environmental Protection Agency. This 26-page "preliminary study" explores and summarizes current knowledge about the environmental considerations and impacts of shale gas exploration and extraction, and in particular the use of hydraulic fracturing technology.
This document provides an overview and introduction to a course on geotechnical engineering at Chinhoyi University of Technology. It covers topics like soil formation, properties of soils, soil classification, soil compaction and permeability. It discusses soil mechanics, different types of soils like residual and alluvial soils. It also explains concepts like weathering, clay mineralogy, basic structural units and types of clay minerals like kaolinite, montmorillonite and illite. The document is intended to help students understand the key principles and applications of soil mechanics in engineering.
O conto de Edgar Allan Poe "Metzengerstein" descreve a rivalidade entre as famílias Berlifitzing e Metzengerstein. O jovem Barão Frederico de Metzengerstein herda grandes propriedades e um cavalo estranho após um incêndio no castelo Berlifitzing que mata o Conde Guilherme. Frederico parece ter uma conexão sinistra com o cavalo e a morte do Conde sugere que ele pode ter causado o incêndio.
La Unión Europea ha acordado un embargo petrolero contra Rusia en respuesta a la invasión de Ucrania. El embargo prohibirá las importaciones marítimas de petróleo ruso a la UE y pondrá fin a las entregas a través de oleoductos dentro de seis meses. Esta medida forma parte de un sexto paquete de sanciones de la UE destinadas a aumentar la presión económica sobre Moscú y privar al Kremlin de fondos para financiar su guerra.
Here are the key points about Chinesegamers' WALKFUN mobile game platform strategy:
- Targets mobile game players in China
- China has a huge and growing mobile games market
- By building a platform, Chinesegamers can aggregate players and games in one place
- This allows them to monetize the platform through things like in-game payments, ads, etc.
- The strategy is to attract both game developers to publish games on the platform for exposure to players
- And to attract players by offering a wide selection of games in one centralized location
So in summary, the key players in their strategy are mobile game developers and players in China. By building a platform, they aim to be the
Este documento presenta los programas de estudio 2011 para la asignatura de Tecnología en la educación secundaria. Explica la fundamentación de la tecnología como una actividad humana, social e histórica, y define los conceptos de técnica y tecnología que se utilizarán. Además, incluye la introducción, fundamentación, enfoque pedagógico, contenidos y bibliografía para los tres grados de secundaria.
This document provides an outline for a thriller film called "The Last Detail" involving a librarian with a dark secret being watched by a mysterious character. The opening scene will show the librarian collecting a briefcase and being observed by the unknown character in the library. The film will be shot in a campus library and involve props like books and a notebook. The librarian's costume and the stalker's shoes are also described. Sound design ideas and a production schedule are included.
El documento contiene varios poemas cortos sobre árboles. Los poemas describen árboles de diferentes formas y colores, y cómo cambian a través de las estaciones. Uno habla de un árbol oscuro que observa a alguien caminando. Otro describe un árbol de madera con hojas amarillentas. Un tercero es sobre un pequeño árbol bonito en un jardín.
This document provides an overview of expectations for officials from an education meeting by the DCHOA. It discusses bylaws, arrival times and attire requirements. The scheduling process involves 3 blocks of games that are pre-assigned and reviewed in meetings by a scheduling committee. Officials are evaluated on ability, experience, attitude and availability. To get more games, officials are encouraged to improve their skills, make themselves available and flexible, and go the extra mile. Coaches, players and partners all have expectations to follow the rules knowledgeably and consistently and communicate well.
El documento habla sobre el caos vehicular en Bogotá durante las horas pico de la mañana y tarde, cuando un viaje de 10 minutos puede tomar 1 hora o más. También menciona que los buses de transporte público contribuyen al caos debido a la "guerra del centavo", pero que el nuevo Sistema Integrado de Transporte (SITP) busca mejorar la movilidad haciéndola más fluida y rápida.
This document provides a summary of pricing insights and analyses published by Oliver Ranson and Ranson Pricing Ltd. during 2016. It includes articles on avoiding common pitfalls when selecting pricing technology, defining customer archetypes, and the benefits of abandoning traditional full-content agreements with global distribution systems. The document outlines the topics covered in each quarter and provides high-level summaries of selected articles.
The document discusses lipids and fats, including their chemical structures and functions. It covers the digestion and absorption of lipids. Key points include:
- Lipids such as triglycerides, phospholipids, and sterols do not dissolve in water. Triglycerides are the main form of lipids and are composed of fatty acids attached to a glycerol backbone.
- Fatty acids can be saturated, monounsaturated, or polyunsaturated depending on the number and location of double bonds. Omega-3 and omega-6 fatty acids are essential.
- Lipids are emulsified and broken down into fatty acids and glycerol in the digestive system before being absorbed and transported by lipoproteins such
Biofouling refers to the undesirable attachment of microorganisms, plants, and animals to submerged surfaces, which can affect industries like shipping and aquaculture. Traditional antifouling technologies use toxic chemicals that harm the environment, but alternatives are being researched, including natural products, foul release coatings, and biological or mechanical controls. Finding effective and environmentally friendly alternatives faces barriers like a lack of globally approved options, unknown long term toxicity, and higher costs compared to traditional chemicals.
MediaEval 2015 - The C@merata Task at MediaEval 2015: Natural Language:Querie...multimediaeval
This was the second year of the C@merata task which relates natural language processing to music information retrieval. Participants each build a system which takes as input a query and a music score and produces as output one or more matching passages in the score. This year, questions were more difficult and scores were more complex. Participants were the same as last year and once again CLAS was the best with a Beat F-Score of 0.620.
http://ceur-ws.org/Vol-1436/
http://www.multimediaeval.org
The Soa Brand is a creative services agency that tells compelling stories through beautifully designed events, weddings, and branding. Founded in 2010 as an events company, The Soa Brand now offers creative services beyond just events. Led by Chief Storyteller Shawntel, The Soa Brand believes every person and brand has a story to tell and works to share those stories through innovative designs and strategies.
This document provides information about wellness programs and events at the Wellness Center for the week of November 5, 2015. It includes details on nutrition classes, group fitness classes, aquatics classes, limited holiday hours, and a spiritual wellness workshop on creating a wellness manifesto. Nutrition classes taught by Marissa Moore on healthy meal preparation are offered on Wednesdays. The document lists various group fitness classes offered in December including indoor cycling, kickboxing, yoga, and Zumba. It also provides recreation center hours for basketball, volleyball, soccer, and more.
The document discusses self-healing concrete that uses bacteria and mineral precursors to seal cracks automatically. Bacteria are added to the concrete along with calcium lactate. When cracks form and water enters, the bacteria metabolize the calcium lactate to precipitate calcium carbonate, sealing the cracks. Early attempts involved direct addition but viability was limited. Newer methods encapsulate the bacteria and precursors in lightweight aggregate added to concrete. Tests show this extends viability to months and allows self-healing of cracks up to 0.5mm wide through bacterial precipitation of minerals. Further optimization is still needed to minimize effects on concrete strength and allow self-healing over the full lifespan of concrete structures.
Next Generation Self-Healing Concrete- Infusing Bacteria into Engineered Ceme...Ben Kaplan
This document discusses a study combining two approaches to self-healing concrete: engineered cementitious composite (ECC) and bacteria. The study infused the bacteria Sporosarcina pasteurii into ECC mixtures and tested self-healing in laboratory, exposed, and underground environments. Results showed bacterial-ECC exhibited greater self-healing than normal ECC, with no significant difference between laboratory and underground environments. Exposure led to negligible self-healing. Compressive strength and absorption tests also indicated compatibility between ECC and bacteria. The successful underground self-healing lays a foundation for further field studies on this novel hybrid material.
Current knowledge on microbial induced problems and biofouling in lubrication...Christer Fjeld
This document discusses microbial induced problems and biofouling in lubrication systems of ships and marine installations. It notes that while such problems are likely rare, microbes are capable of colonizing lubrication systems if water is present. A variety of industries can be affected by microbial growth in lubrication systems, including shipping, metalworking, and hydroelectric power. Environmentally acceptable lubricants may be more prone to biodegradation compared to traditional petroleum-based lubricants due to their higher biodegradability. Increased monitoring of microbial issues is important as these alternative lubricants are more widely used.
Navigating the Seas of Biofouling Strategies for Effective Management.docxShelton05
Biofouling, the accumulation of marine organisms on submerged surfaces, poses significant challenges across various industries, including shipping, aquaculture, and offshore energy production. This natural process not only impacts the performance and efficiency of marine structures but also raises environmental concerns due to the potential spread of invasive species. As the global maritime industry continues to expand, effective biofouling management strategies are essential to mitigate economic and ecological consequences.
O conto de Edgar Allan Poe "Metzengerstein" descreve a rivalidade entre as famílias Berlifitzing e Metzengerstein. O jovem Barão Frederico de Metzengerstein herda grandes propriedades e um cavalo estranho após um incêndio no castelo Berlifitzing que mata o Conde Guilherme. Frederico parece ter uma conexão sinistra com o cavalo e a morte do Conde sugere que ele pode ter causado o incêndio.
La Unión Europea ha acordado un embargo petrolero contra Rusia en respuesta a la invasión de Ucrania. El embargo prohibirá las importaciones marítimas de petróleo ruso a la UE y pondrá fin a las entregas a través de oleoductos dentro de seis meses. Esta medida forma parte de un sexto paquete de sanciones de la UE destinadas a aumentar la presión económica sobre Moscú y privar al Kremlin de fondos para financiar su guerra.
Here are the key points about Chinesegamers' WALKFUN mobile game platform strategy:
- Targets mobile game players in China
- China has a huge and growing mobile games market
- By building a platform, Chinesegamers can aggregate players and games in one place
- This allows them to monetize the platform through things like in-game payments, ads, etc.
- The strategy is to attract both game developers to publish games on the platform for exposure to players
- And to attract players by offering a wide selection of games in one centralized location
So in summary, the key players in their strategy are mobile game developers and players in China. By building a platform, they aim to be the
Este documento presenta los programas de estudio 2011 para la asignatura de Tecnología en la educación secundaria. Explica la fundamentación de la tecnología como una actividad humana, social e histórica, y define los conceptos de técnica y tecnología que se utilizarán. Además, incluye la introducción, fundamentación, enfoque pedagógico, contenidos y bibliografía para los tres grados de secundaria.
This document provides an outline for a thriller film called "The Last Detail" involving a librarian with a dark secret being watched by a mysterious character. The opening scene will show the librarian collecting a briefcase and being observed by the unknown character in the library. The film will be shot in a campus library and involve props like books and a notebook. The librarian's costume and the stalker's shoes are also described. Sound design ideas and a production schedule are included.
El documento contiene varios poemas cortos sobre árboles. Los poemas describen árboles de diferentes formas y colores, y cómo cambian a través de las estaciones. Uno habla de un árbol oscuro que observa a alguien caminando. Otro describe un árbol de madera con hojas amarillentas. Un tercero es sobre un pequeño árbol bonito en un jardín.
This document provides an overview of expectations for officials from an education meeting by the DCHOA. It discusses bylaws, arrival times and attire requirements. The scheduling process involves 3 blocks of games that are pre-assigned and reviewed in meetings by a scheduling committee. Officials are evaluated on ability, experience, attitude and availability. To get more games, officials are encouraged to improve their skills, make themselves available and flexible, and go the extra mile. Coaches, players and partners all have expectations to follow the rules knowledgeably and consistently and communicate well.
El documento habla sobre el caos vehicular en Bogotá durante las horas pico de la mañana y tarde, cuando un viaje de 10 minutos puede tomar 1 hora o más. También menciona que los buses de transporte público contribuyen al caos debido a la "guerra del centavo", pero que el nuevo Sistema Integrado de Transporte (SITP) busca mejorar la movilidad haciéndola más fluida y rápida.
This document provides a summary of pricing insights and analyses published by Oliver Ranson and Ranson Pricing Ltd. during 2016. It includes articles on avoiding common pitfalls when selecting pricing technology, defining customer archetypes, and the benefits of abandoning traditional full-content agreements with global distribution systems. The document outlines the topics covered in each quarter and provides high-level summaries of selected articles.
The document discusses lipids and fats, including their chemical structures and functions. It covers the digestion and absorption of lipids. Key points include:
- Lipids such as triglycerides, phospholipids, and sterols do not dissolve in water. Triglycerides are the main form of lipids and are composed of fatty acids attached to a glycerol backbone.
- Fatty acids can be saturated, monounsaturated, or polyunsaturated depending on the number and location of double bonds. Omega-3 and omega-6 fatty acids are essential.
- Lipids are emulsified and broken down into fatty acids and glycerol in the digestive system before being absorbed and transported by lipoproteins such
Biofouling refers to the undesirable attachment of microorganisms, plants, and animals to submerged surfaces, which can affect industries like shipping and aquaculture. Traditional antifouling technologies use toxic chemicals that harm the environment, but alternatives are being researched, including natural products, foul release coatings, and biological or mechanical controls. Finding effective and environmentally friendly alternatives faces barriers like a lack of globally approved options, unknown long term toxicity, and higher costs compared to traditional chemicals.
MediaEval 2015 - The C@merata Task at MediaEval 2015: Natural Language:Querie...multimediaeval
This was the second year of the C@merata task which relates natural language processing to music information retrieval. Participants each build a system which takes as input a query and a music score and produces as output one or more matching passages in the score. This year, questions were more difficult and scores were more complex. Participants were the same as last year and once again CLAS was the best with a Beat F-Score of 0.620.
http://ceur-ws.org/Vol-1436/
http://www.multimediaeval.org
The Soa Brand is a creative services agency that tells compelling stories through beautifully designed events, weddings, and branding. Founded in 2010 as an events company, The Soa Brand now offers creative services beyond just events. Led by Chief Storyteller Shawntel, The Soa Brand believes every person and brand has a story to tell and works to share those stories through innovative designs and strategies.
This document provides information about wellness programs and events at the Wellness Center for the week of November 5, 2015. It includes details on nutrition classes, group fitness classes, aquatics classes, limited holiday hours, and a spiritual wellness workshop on creating a wellness manifesto. Nutrition classes taught by Marissa Moore on healthy meal preparation are offered on Wednesdays. The document lists various group fitness classes offered in December including indoor cycling, kickboxing, yoga, and Zumba. It also provides recreation center hours for basketball, volleyball, soccer, and more.
The document discusses self-healing concrete that uses bacteria and mineral precursors to seal cracks automatically. Bacteria are added to the concrete along with calcium lactate. When cracks form and water enters, the bacteria metabolize the calcium lactate to precipitate calcium carbonate, sealing the cracks. Early attempts involved direct addition but viability was limited. Newer methods encapsulate the bacteria and precursors in lightweight aggregate added to concrete. Tests show this extends viability to months and allows self-healing of cracks up to 0.5mm wide through bacterial precipitation of minerals. Further optimization is still needed to minimize effects on concrete strength and allow self-healing over the full lifespan of concrete structures.
Next Generation Self-Healing Concrete- Infusing Bacteria into Engineered Ceme...Ben Kaplan
This document discusses a study combining two approaches to self-healing concrete: engineered cementitious composite (ECC) and bacteria. The study infused the bacteria Sporosarcina pasteurii into ECC mixtures and tested self-healing in laboratory, exposed, and underground environments. Results showed bacterial-ECC exhibited greater self-healing than normal ECC, with no significant difference between laboratory and underground environments. Exposure led to negligible self-healing. Compressive strength and absorption tests also indicated compatibility between ECC and bacteria. The successful underground self-healing lays a foundation for further field studies on this novel hybrid material.
Current knowledge on microbial induced problems and biofouling in lubrication...Christer Fjeld
This document discusses microbial induced problems and biofouling in lubrication systems of ships and marine installations. It notes that while such problems are likely rare, microbes are capable of colonizing lubrication systems if water is present. A variety of industries can be affected by microbial growth in lubrication systems, including shipping, metalworking, and hydroelectric power. Environmentally acceptable lubricants may be more prone to biodegradation compared to traditional petroleum-based lubricants due to their higher biodegradability. Increased monitoring of microbial issues is important as these alternative lubricants are more widely used.
Navigating the Seas of Biofouling Strategies for Effective Management.docxShelton05
Biofouling, the accumulation of marine organisms on submerged surfaces, poses significant challenges across various industries, including shipping, aquaculture, and offshore energy production. This natural process not only impacts the performance and efficiency of marine structures but also raises environmental concerns due to the potential spread of invasive species. As the global maritime industry continues to expand, effective biofouling management strategies are essential to mitigate economic and ecological consequences.
A REVIEW ON SYNTHESIS AND DEVELOPMENT OF SUPERHYDROPHOBIC COATINGIRJET Journal
This document reviews methods for developing superhydrophobic coatings. Superhydrophobic surfaces have water contact angles greater than 150° and are inspired by structures in nature. Common fabrication techniques discussed include chemical etching, dip coating, spin coating, spray coating, electrochemical deposition, sol-gel processing, chemical vapor deposition, and hydrothermal methods. These techniques can be used to create micro/nanostructures and apply low surface energy materials to surfaces, resulting in water-repellent superhydrophobic coatings. Such coatings have applications in industries like marine, aerospace, and energy due to properties like corrosion resistance, self-cleaning, and drag reduction.
The document discusses the role of individuals in preventing pollution. It outlines several types of pollution including water, noise, marine, air, thermal, nuclear, and soil pollution. For each type, it describes the pollution and provides measures individuals can take to reduce or prevent it. The document emphasizes that while governments and industries play a role, individuals are ultimately responsible for pollution and must make efforts such as proper waste disposal, reducing consumption, and spreading awareness to curb pollution.
This document provides a review of amphibious houses as a solution to flooding. It begins with an abstract discussing how population growth is increasing housing needs and environmental impacts. It then reviews 5 previous studies on amphibious housing concepts, methods, findings and applications. The objective, architecture, and methodology of amphibious houses are described. The houses are designed to float during floods and return to their original position when waters recede, allowing occupants to remain in their homes safely. The review concludes by acknowledging contributions and references several previous studies on amphibious housing designs.
This document discusses research into how marine biofouling affects the durability of concrete sea defences. The research investigates how cleaning methods can alter the susceptibility of concrete to algal growth and how factors like nutrients, surface roughness, and moisture influence colonization. A predictive model will be developed to show how cleaning impacts colonization over time. Trials are testing photocatalytic self-cleaning concrete coatings to reduce maintenance costs by destroying organic pollutants that cause deterioration. The research aims to understand how surface topography and coatings can prevent spore settlement and develop long-term testing of coatings and precast units in marine environments.
A STUDY ON REDUCTION OF NITRATE FROM INDUSTRIAL CUM MUNICIPAL WASTEWATER USIN...IRJET Journal
1. The document discusses using MBBR technology to remove nitrates from industrial and municipal wastewater using polyurethane sponge bio-carriers.
2. It summarizes previous studies that found MBBR with PU carriers can achieve simultaneous nitrification and denitrification to efficiently remove total nitrogen at low levels.
3. The document also reviews literature that showed increasing the packing fraction of PU sponge carriers in an MBBR reactor improved nitrate removal through SND processes.
Self-healing concrete has the ability to automatically repair cracks without external intervention. It exists as a spray, mortar, or within the concrete mixture. Cracks are inevitable in concrete over time due to loads and deterioration. Self-healing concrete helps prevent further cracking through two main mechanisms: bacteria that precipitate minerals to fill cracks or capsules containing chemicals that bond when cracks form. While initial costs are high, it reduces long-term maintenance. The concrete has improved durability, permeability and applications in infrastructure but bacteria use remains costly and strength increases slowly.
How nanotechnology affect biodiversity and ecosystem by shreya modiShreya Modi
This document discusses how nanotechnology can help address issues related to biodiversity and ecosystems. It describes how nanotechnology can help develop sustainable energy sources, treat wastewater, aid in oil spill cleanup, and enable better and more affordable medical treatment. The document provides multiple examples of how nanomaterials and nanoscale processes are already being used or explored to solve environmental problems and support human health and well-being while reducing environmental impacts.
Evaluating Interface Properties and Predicting Landfill Liner Stability Under...MrEddyAsyrafSyed
Predicting landfill stability and maintaining stable configuration during filling is responsibility of engineers. Majority of failures occurs within waste mass and along landfill liners. This paper will discuss the methods adopted to predict landfill liner stability in terms of interface performances. Interfaces shear strength parameter evaluation for landfill liner systems have been a tedious testing process.
STUDY ON SELF-HEALING CONCRETE TYPES – A REVIEWIRJET Journal
This document provides a review of different types of self-healing concrete. It discusses two main types: autogenous healing concrete and autonomous healing concrete. Autogenous healing occurs through continued hydration of unreacted cement particles in cracks. Autonomous healing uses encapsulated healing agents like bacteria, polymers or minerals that fill cracks when the capsules rupture. The document examines various mechanisms and factors for bacterial self-healing concrete specifically, including different bacteria types used and how they precipitate minerals to seal cracks. It also reviews capsule-based self-healing concrete using microcapsules filled with substances like epoxy or polyurethane that react to fill cracks when released.
The document discusses the role of individuals in preventing pollution. It outlines several types of pollution including water, noise, marine, air, thermal, nuclear, and soil pollution. For each type, it describes what the pollution is and provides measures individuals can take to control it. The document emphasizes that while governments and industries play a role, individuals are ultimately responsible for pollution and must make efforts to reduce causes of pollution in their daily lives and raise awareness in their communities.
This document summarizes a study investigating microbiologically influenced corrosion of mooring chains through field tests conducted offshore in West Africa. Steel coupons attached to "microbial baiting kits" were deployed at two test sites for several weeks to capture biofilm-forming microorganisms. Analysis of the bacterial DNA from the recovered coupons and surrounding seawater showed that the microbial communities in the biofilms differed from the seawater and indicated sulfate-reducing bacteria were more abundant in biofilms where more severe pitting corrosion was observed. While the field tests provided evidence of microbiologically influenced corrosion contributing to observed corrosion, further work is needed to identify specific microorganisms involved.
Introduction of Environment Technology & Marine Environmental Biotechnology.pptxUniversity of Chittagong
- Biofouling is the accumulation of microorganisms, plants, algae, or small animals on wet surfaces submerged in water. It begins within minutes of a surface contacting water.
- It causes major economic losses by increasing drag on ships and requiring higher maintenance costs. It also facilitates the spread of invasive species globally.
- Various antifouling technologies have been used to prevent biofouling, including coating surfaces with biocides like tributyltin and copper. However, these chemicals are toxic and have led to bans. Alternative methods include using non-toxic coatings and extracting natural antifouling compounds from marine organisms.
Bioremediation uses microorganisms or plants to remove pollutants from the environment. There are two main types - in situ treats pollutants on site, while ex situ removes pollutants to off-site facilities. Examples of in situ techniques include bioventing, biosparging, and in situ biodegradation which supply oxygen and nutrients to stimulate bacteria. Ex situ methods include slurry and aqueous reactors which process contaminated materials in a contained system. Bioremediation can degrade pollutants like copper but has limitations such as environmental constraints and long treatment time.
1. The document discusses self-healing concrete, also known as bio-concrete, which uses bacteria to autonomously repair cracks in concrete.
2. The bacteria and nutrients used to produce calcium carbonate are embedded in expanded clay pellets distributed throughout the concrete mix. When cracks form and water enters, the pellets rupture, releasing the bacteria which metabolize the nutrients to precipitate calcium carbonate and seal the cracks.
3. Experiments found this bacterial self-healing method could fully heal cracks up to 0.5mm wide by producing calcium carbonate through the bacteria's metabolic activity. This self-healing improved the concrete's water tightness and durability.
“Ganga River Sand is Biocalcified to Increase Shear Strength Behaviour for Er...IRJET Journal
This document summarizes a study on using microbially induced calcite precipitation (MICP) to improve the shear strength properties of Ganga River sand for erosion control applications. The study involves treating samples of fine-grained Ganga River sand with urea and calcium solutions and Bacillus bacteria cultures. After 18 days of treatment at room temperature, analysis found increased stiffness, shear strength, and calcite content in treated samples compared to untreated samples. The document concludes that MICP has potential for soil improvement and erosion control by binding soil particles with precipitated calcite and improving soil properties.
Similar to Adam Brann_i7714566_Advanced Engineering (20)
“Ganga River Sand is Biocalcified to Increase Shear Strength Behaviour for Er...
Adam Brann_i7714566_Advanced Engineering
1. 1 eBU: Online Journal, 1(1) December 2015, PP. 1-X
Reducing bio-fouling on horizontal axis tidal turbines using
engineered surface microstructures
Adam Branna
a
Faculty of Science and Technology, Department of Design and Engineering, Bournemouth
University, BH12 5BB, UK
ABSTRACT
This journal paper explores existing methods of anti-fouling in various industries, and discusses the viability
of using novel surface solutions to combat bio-fouling on horizontal axis tidal stream generators, increasing
the reliability and financial viability of such systems. It is found that microtopographies show excellent
antifouling properties in test conditions. The real life implications of fouling on microstructures are discussed,
and it is suggested that the application of engineered surface microstructures will not be financially viable
until and automated solution for applying them to large scale structures is found.
1. INTRODUCTION
In a time where the UK’s demand for electricity is
expanding, with its steadily growing population, and
heating and transport have become increasingly
electrified (UK Gov 2012), there is a growing interest
in renewable electricity generation.
Tidal energy is an emerging process of renewable
electricity generation, currently in the pre-
commercialisation phase, with only a few plants
nationwide (UK Gov 2012). Tidal energy is divided
into two sub-categories, tidal range and tidal stream.
Tidal range solutions allow a reservoir to be filled by
the incoming tide, and then allow the reservoir to
drain once the tide has receded, turning turbines to
create electricity. Tidal stream solutions capture the
kinetic energy of the flowing water (TEL 2015).
There are a number of different technologies
available for tidal stream energy conversion,
including oscillating hydrofoils, horizontal axis tidal
turbines (HATTs) and vertical axis turbines (EMEC
2008). The most widespread technology is
horizontal axis, with 11 full scale systems in
operation (Green Rhino Energy 2015). HATTs may
be bottom anchored, or mounted on floating tethered
platforms.
Figure 1.Example of a horizontal axis tidal stream energy
converter in Ireland, the SeaGen S (Sea Generation ltd.
2015).
The UK is the world leader in the development of the
emerging tidal stream sectors, and the government
have set aside “a ring fenced revenue support for
100MW of wave and tidal stream up to 2019” (UK
Gov 2014). Although at present, government reports
show the contribution to be negligible, (UK Gov
2015), the government predicts that by 2020, tidal
energy will have begun to play an increasing role in
electricity generation. (UK Gov 2011). In light of this,
it is important that we understand the potential
problems and barriers to the widespread adoption of
tidal stream technology. One such problem, and the
problem that will be focused on in this paper, is bio-
fouling.
Despite having significant merits for the marine eco-
system, biofilms are better known for their
detrimental effects on manmade structures. (Davey
et al 2000; Killea 2014). Biofouling has plagued the
shipping industry for centuries (Field 1981; Hamm
2009; AkzoNobel 2013), colonising submerged
sections of the hull and generating drag. A study
performed by Schultz (2011, pg91) on a boats hull
reported increased resistance of 9% with light
fouling, increasing to 69% with heavy calcareous
fouling. Such drastic increase in resistance would
significantly affect the performance of the blade, by
reducing the lift drag-ratio (Almukhtar 2012). Orme
et al. (2001, p.99) conducted an experiment
simulating the effects of barnacle growth on a marine
turbine blade. Results showed that low levels of
barnacle fouling caused losses of 20%, and higher
levels could cause a 70% decrease in efficiency. As
well affecting the hydrodynamics of the blades,
fouling can induce microbial influenced corrosion
(MIC). MIC is defined as the acceleration of
corrosion due to the presence of biofilms (Beech
2000; Beech 2004; Mijle-Meijer 2009). MIC can
result costly unexpected maintenance, potentially
increasing the cost of electricity produced. Turnock
(2009) states, ‘The key to the success of tidal
turbines is their ability to operate in the ocean for
extended periods with minimal intervention (15-20
years)’. It is clear that for such lifespans, an effective
antifouling solution must be chosen.
2. 2 Reducing the biofouling of tidal turbines using surface microstructures
2. Biofouling
In the marine environment, ‘Biofouling’ is the
colonisation of submerged surfaces by unwanted
organisms such as bacteria, barnacles and algae.
(AMBIO 2010). In our context, biofouling is the
attachment and growth of undesirable molecules
and organisms to submerged surfaces. (Rittschof
2009). Biofouling has 4 main stages (see figure.1),
which occur in succession to one another. The first
layer, the conditioning film (often referred to as
‘biofilm’), is comprised of media on a microbial scale;
proteins, polysaccharides, organic and inorganic
substances. (Bruijs 2006). Organisms on this scale
either ‘choose’ where to settle (motile), or change
shape to ‘fit’ the micro topography of the substrate.
In the marine environment, practically all surfaces
are eventually colonized with a bio-film (Turnock
2009). Once the conditioning film has colonised the
substrate layer, it attracts bacteria, micro-algae and
fungi, which form the 2nd and 3rd layers, and along
with the conditioning film, form the micro-fouling
community. Finally, invertebrates, seaweed and
other animals are attracted, and form the
Macrofouling community. It is important to note, that
all layers of fouling need to attach to the substrate
itself in order to feed, grow and reproduce, rather
than settling on top of the conditioning film (Field
1981) (Bruijs 2006). Furthermore, Walker et al.
(2014, p.266) state that, “The tenacity of the biofilm
is affected by a range of variables including, but not
limited to, composition, substrate, and a host of
environmental factors. It follows that a solution must
pertain to the substrate itself.
2.1 State of the art antifouling measures
Presently the majority of antifouling solutions falls
under two categories; chemically active antifouling
(biocide containing) coatings, and non-toxic
antifouling (biocide free). (AkzoNobel 2014a). Both
systems are paints, usually applied in two layers.
The primer applied directly to substrate normally
contains anti-corrosive functions. The topcoat, the
layer with which marine life will interface with,
changes depending on the system. (Chambers
2006).
2.11 Chemically active antifouling
Chemically active coatings work by secreting
biocides. Biocides are chemical substances or
mixtures used for the elimination of living
organisms through chemical or biological action
(European environmental bureau 2014). The main
driver dictating development in biocidal antifouling
technology is legislation (AkzoNobel 2010). There
are two key techniques for controlling the release of
antifouling compounds from a coating by using
either a soluble or insoluble matrix (Chambers
2006) (see figure. 3). Chemically active antifouling
technologies can be subdivided into 2 more
categories; Contact leaching, and soluble matrix
(Bressy 2009). Antifouling systems are distinctive
from each other in both their microstructure and
rosin content. In coatings where the rosin content is
low, the coatings are “contact leaching” coatings
(AkzoNobel 2014b; Dennington 2015) Contact
leaching coatings are mechanically tough, with a
maximum service life of 18-24 months, (AkzoNobel
2014b) (Pei and Ye 2015). The service life is
proportional to the amount of biocide incorporated,
the coating thickness remains the same while the
biocide depletes (Bressy 2009). Contact leaching
coatings consist of an insoluble matrix structure,
‘filled’ with a soluble medium, rosin, and biocides.
The rosin and biocide diffuse upon contact with
seawater, leaving an empty skeleton of insoluble
material, which is what the coating owes its
mechanical strength to. The leaching of biocides is
non-liner: the biocide will leach rapidly when freshly
applied, and become less effective with time
(Berendsen 1989).
Figure 2. Schematic view of the four main stages of marine
biofouling. (Bruijs 2006)
Figure 3. Schematic of (a) soluble matrix biocide releasing
coating and (b) insoluble biocide releasing coating.●
Antifoulant loaded,○ depleted antifoulant. (Chambers 2006)
3. 3 Adam Brann
Coatings in which the rosin level is high are
“soluble matrix” coatings. There are two main types
of soluble matrix coatings; Controlled depletion
polymer, and self-polishing copolymers. Controlled
depletion coatings allow seawater to penetrate the
paint, releasing the biocides by diffusion
(Goodes.L.R, 2014). They are designed to release
biocides at a constant rate (Kiis.S, 2009), thus
providing stable and relatively predictable
antifouling.
Self-polishing copolymers (SPC’s) also
have a soluble microstructure. The soluble matrix
allows seawater to penetrate the matrix, and
through hydrolysis, strip the biocide from the
polymer, which is chemically linked to the biocide
(see figure.3) (Chambers 2006) (Dennington 2015).
As the surface depletes, the resin ‘smooth’s over’
microscopic fissures caused by the erosion of the
coating, leaving a smoother underlying surface
(Omae 2003; Kiis 2009), hence the name ‘self-
polishing’. The reduced skin friction is obviously a
benefit to the hydrodynamic properties of the
surface. SPC’s have the best long term
performance of chemically active anti-fouling’s
(Bressy 2009), and have a service life of up to 60
months (AkzoNobel 2010).
In 2008, the most popular and effective SPC,
Tributyltin-Tin (TBT) was banned from the shipping
industry for its adverse effects on the marine
ecosystem. (Doyle 2014). SPC now contains less
virulent biocides. The prohibition of TBT spawned
new interest in the development of foul release
coatings (Altar 2003).
2.12 Non-Toxic Antifouling
Foul release coatings are biocide free,
hydrophobic, ‘non-stick surfaces. A combination of
low surface tension and low wettability makes it
difficult for organisms to adhere to the surface of
the coating (Atlar 2003; Baier 2006; Carman 2006;
Magin et al. 2010). Biofouling that manages to
adhere does so very weakly, and is removed by the
shear forces incurred by the movement of water
past the surface (Candries 2001). Current coatings
require 10-15 knots of flow perpendicular to the
surface to remove fouling (Solomon 2014;
AkzoNobel 2015a). Experiments by Baier (2006)
found that
biofouling organisms exhibited the lowest relative
adhesion on materials with surface tensions
approximately 22 mN/m (see figure.4). Current foul
release polymers are normally
Polydimethylsiloxane (PDMS) based (Magin et al.
2010; Lindholt 2015; Thorlaksen et al. 2015) due to
its surface tension - 20-23 mN/m (Potter 1996;
Grunde et al. 2008). Thickness also plays an
important role in foul release coatings – it has been
shown that barnacles can cut through coatings
below ~100µm, and adhere securely to the
underlying primer (Candries 2001; Altar 2003).
Above this thickness there is no increase in fouling
release properties (Altar 2003). Experiments by
Candries.M (2001) showed that foul release
coatings incurred less drag than SPC coatings,
when first applied. As there is no chemical change,
polishing function or any film degradation, the
service life of the coating is governed by the
amount of wear the coating is subjected to
(AkzoNobel 2015b).
3. Surface Microstructure
The microstructure of a material is simply described
as the appearance of a material on a nano-micro
meter scale. (ASM 1985; Cavendish laboratory
2013). Examples of antifouling microstructures can
be found in nature; sharkskin consists of a matrix of
‘denticles’ (figure. 5) that reduce its drag whilst
swimming, by
disrupting the flow of water (Wen.L et al. 2014). The
lotus leaf has a very rough microstructure, which is
Figure 4. Self-Polishing copolymers (Dennington 2015)
Figure. 6. Examples of surface microstructures in nature. Left:
CGI of the lotus leafs' microstructure. Right: Shark skin
denticles (Thieckle 2015; Sewell 2015)
Figure 5. The Baier Curve (Baier 2006)
4. 4 Reducing the biofouling of tidal turbines using surface microstructures
responsible for its super-hydrophobic, self-cleaning
surface (Figure. 5). The periostraca on blue mussels
and crabs are effective antifouling surfaces (Magin
et al. 2010). Epoxy resin replicates of the periostraca
reduced fouling for 3-4 weeks (Bers 2004). Magin et
al. (2010) suggests that the short term performance
implies that natural antifouling is a combination of
chemistry and micro topography. Using modern
techniques, it is possible to construct ‘man-made’
engineered surface microstructures. Engineered
microstructures take on two forms; Micro-
topographical, and self-assembled monolayers.
3.11 Topographical Microstructures
It is possible to impose microscopic patterning on a
surface using a variety of techniques such as laser
etching, photolithography, and nano-imprinting
(Lee.W et al. 2004; Groenendijk 2008; Magin et al.
2010). The topography on a micro-scale affects
mechanical friction, optical properties, and
bioadhesion (Lee.W et al. 2004) as well as the
wettability of a surface (Groenendijk 2008; Lin.F et
al. 2011; Lamberti 2012).
The pattern with which the substrate is imprinted has
an effect on the properties of the material. In an
experiment by Carman et al. (2006), it was found that
different micro patterns (see figure 7.) on treated
PDMS (PDMSe) exhibited different contact angles
with water droplets. Pits and ridges increased the
contact angle by approximately 7°. Channels, and a
bio-inspired antifouling surface, Sharklet AFTM ,
increased the contact angle by 25° and 27°
respectively, compared to smooth PDMSe. Carman
(2006) suggests that wettability and settlement of
biofilm agents (spores, bacteria) can be modelled
using the same principles; surfaces that encourage
the Cassie-Baxter wetting state (Cassie and Baxter
1944) will encourage cells to ‘bridge’ the peaks of the
microstructures. Similarly, a surface that encourages
the Wenzel wetting state, will encourage cells to
pack into the ‘valleys’ of microstructure (Wenzel
1936; Carman 2006). The state of bridging offers the
alien cells less surface area to adhere to, and
reduces the strength of the adhesion. (Carman et al.
2006; Athavale 2010).
3.12 Current applications
The SharkletTM micropattern has applications in the
health sector, for reducing bacterial infection on
invasive equipment, such as catheters and
endotracheal tubes (Sharklet 2015). The pattern can
be applied to ‘high touch surfaces’ in hospitals such
as doors, in the form of an adhesively backed film.
An anti-bacterial surface that works through
topography alone pre-empts the immunisation of
superbugs such as MRSA to existing chemical
solutions. Carman et al. (2006) found that a
SharkletTM microstructure was able to reduce the
settlement of zoospores by up to 85% compared to
smooth control surfaces. In another study, Mann
(2014) found that the SharkletTM pattern reduced
MRSA attachment by 98%. In the aerospace sector,
Lufthansa Technik is currently experimenting with
imprinting riblet microstructures into paints on
aircraft to reduce turbulence perpendicular to the
direction of airflow (Gubisch 2013; Lufthansa
Technik, 2015a). Using, ‘Simultaneous stamp
hardening’. Simultaneous stamp hardening works in
a similar way to nano imprinting (citation), but
instead of a stainless steel mould, a transparent
silicon negative of the microstructure is applied
directly to the freshly painted lacquer (Lufthansa
Technik 2015b). The coating is then immediately
cured with UV light (Gubisch 2013; Lufthansa
Figure 7. Examples of different topographical patterns A:
Pillars, B:Pits, C:Channels, D:Ridges, E:Sharklet AFTM
(Carman 2006)
Figure 8. a) Wenzel state b) Cassie-Baxter state (Bridging)
(Rodriguez 2012)
5. 5 Adam Brann
Technik 2015b).A robotic arm is being developed to
automatically apply the coating, as applying the
coating manually to large surface areas is not
deemed cost effective. The coating is expected to
increase fuel efficiency by 1%, and will finish in 2017
(Lufthansa Technik 2015a).
3.2 Self-assembling monolayers
Self-assembling monolayers (SAMs) are ‘grown’ on
substrates (Mahajan 2010). They are organic
assemblies formed by the absorption of molecules
from a liquid or gas (Schreiber 2000; Love et al.
2005; Mahajan 2010). The absorbed molecules ‘self-
assemble’ to form a regular crystalline layer around
1-3µm thick on a metallic substrate (Love et al.
2005). SAMs can be configured to be hydrophobic
or hydrophilic. Unlike topographical microstructures,
the production of SAMs does not require specialist
equipment, and are easy to prepare (Schreiber
2000; Love et al. 2005). A SAM consists of 2 main
parts; a metallic layer, usually gold for its chemical
inertness (Love et al. 2005; Nugraha et
al. 2015), but other metals such as silver, copper and
palladium have been extensively studied (Laibinis et
al. 1991; Love et al. 2003). The metallic layer is often
applied as a film on a glass (Taglietti 2014) or silicon
substrate (Love et al. 2005; Zhang 2012). The
second layer is comprised of a chain of alkanes. The
composition of the alkane chain depends on the
solution that the substrate is exposed to. The chains
are fragile due to their minute scale.
SAMs have been shown to repel the settlement of
proteins (Chapman et al. 2000; Ederth et al. 2011),
as well as displaying excellent antifouling against
cyprids (Barnacle larvae), polysaccharides and algal
spores (Ederth 2011). Hydrophilic SAMs are
expected to be effective against foulers that secrete
hydrophobic adhesive, and hydrophilic SAMs are
effective against foulers with hydrophobic adhesive
(Li et al. 2015).
DISCUSSION
Topographical microstructures: A possible
solution?
Microtopographies have been shown to reduce the
settlement of bacteria on their surfaces. The
SharkletTM micro-pattern has demonstrated high
resistance in test conditions, reducing settlement up
to 98% over a set amount of time. In the situation of
a tidal turbine, reducing the settlement alone is not
good enough. Over a longer period of time, fouling
will eventually form, albeit slower on a surface with
resistance. The surface needs to have a way of
removing fouling from its surface. Coatings must
have a method of removing settled growth. Biocidal
paints remove growth by killing it, foul release
coatings rely on the flow of water to self-clean.
With respect to self-cleaning, topographical
microstructures would be expected to function in a
similar way to a foul release coating. If organisms do
manage to adhere, the coatings rely on the shear
force of the water to remove the fouling. It follows
that the hydrodynamic environment in which these
coatings will be applied is of great importance to their
efficacy.
The speed of the water past the anchor surface of
the turbine is dependent on the tidal stream speed.
The relative speed over the rotating blades surface
is the resultant of the angular speed of rotation and
the tidal stream speed, which changes along the
length of the blade (see figure 11). The current in
which most existing turbines operate is 2-3ms-1
(PMSS 2006; Power Technology 2015). On a static
structure, such as the anchoring pillar of a bottom
mounted turbine, or the platform of a surface
mounted tethered turbine, the speed of flow would
be too low for existing foul release paints, which
require at least 5ms-1. In the absence of
experimental proof, it’s impossible to categorically
state that a topographical microstructure could
achieve foul release at speeds of 2-3ms-1. It may be
speculated that a microstructure that encourages a
‘bridging’ state provides less surface area to adhere
but retains the critical surface tension of
approximately 22Mn/M; would encourage adhesive
bonds of weaker strength than on foul release
coatings. In reality, while this may be true in a
controlled laboratory environment, it is unlikely to
work for a marine environment. Current tests haven’t
taken into account the presence of other organisms,
sediment, or inorganic particles. It is possible that
particles of sediment or microscopic organisms
smaller than the channel width of the micro pattern
could settle in the channels, producing a surface that
Figure 10. Schematic diagram of an ideal crystalline SAM (Love
et al. 2005)
Figure 9. Riblet microstructure impressed in lacquer using
'simultaneous stamp hardening' (Lufthansa Technik 2014)
6. 6 Reducing the biofouling of tidal turbines using surface microstructures
is likely to encourage a Wenzel-style state of fouling,
rather than the preferred Cassie-Baxter state. Media
that settles in the channels will become sheltered
from the flow to a degree, if the pattern isn’t aligned
perfectly with the current and as a consequence,
exacerbate the fouling situation.
Microstructures have been shown to enhance flow
properties by reducing cross axial drag, as shown in
nature, by the microstructure of sharkskin, and in
aerospace by Lufthansa Techniks’ riblet
microstructure. These microstructures are suited to
high speed turbulent flow conditions, in laminar flow
hydraulically smooth surfaces produce less drag.
Tidal stream currents are normally turbulent (Lynn
2014), but relatively low speed. Should the
microstructure reduce drag in this condition, the
turbine would be able to achieve higher efficiency.
Regardless of whether microtopographies can
achieve this, their viability still hinges on their ability
to effectively deter fouling and self-clean; fouling
would eventually incur more drag than the
microtopography reduces.
Application of microtopographies
Work by Bers (2004) demonstrated the fact that
fouling is not deterred by the micro pattern alone. It
follows that the substrate into which they are printed
must also have antifouling properties. Previous
studies suggest PDMS is the most effective
substrate to use.
The application of surface microstructures to
horizontal axis tidal turbines (HATTs) is a complex
problem. I suggest that topographical
microstructures could be applied in to horizontal axis
tidal turbines in two ways, either as a cladding,
where the topography is prepared on PDMS ‘tiles’,
which are then adhered to the surfaces of
components, or are imprinted into a foul release
style paint, using a process similar to simultaneous
stamp hardening. The cladding method would
comply with traditional methods of creating micro
topographies, imprinting or photolithography, and
damaged sections could be easily stripped from
HATTs surface and replaced with a new tile.
However, this method has a number of flaws. The
PDMS substrate that they are normally imprinted
onto is inherently ‘non-stick’, thus making it difficult
to stick to surfaces with conventional adhesives. The
selection of adhesive is further complicated by the
submarine environment it has to endure. There
would inevitably be discontinuities in the pattern at
the interface between tiles, affecting the AF
properties of the pattern. Finally, adhering the tiles to
a surface with a relatively tight radius, such as the
leading edge of a turbine blade, would warp the
pattern, elongating the ‘valleys’ of the
microstructure, allowing spores and microbes to
settle within the valleys rather than bridging them.
The simultaneous stamp hardening method offers
more promise, it could be assumed less discontinuity
in the pattern would occur. A bespoke paint would
need to be formulated with similar properties to foul
release coatings, but also able to cure rapidly in UV
light. At present the process is carried out by hand.
Application of engineered microstructures to HATTs,
or any large scale assemblies will be extremely
labour intensive in the absence of automation. The
cost-effectiveness of both solutions will be vastly
increased in the presence of an automatic
application process. A robotic solution such as the
arm being developed by Lufthansa Technik would
dramatically increase the financial viability of
applying microtopographies to large scale
structures.
Applying microtopographies to existing turbines
would be extremely difficult, not least because of the
awkward location HATTs are in. Retrofitting
permanently submerged areas of the turbine would
be impossible. Turbines which allow the drivetrain to
be raised above water, such as the Seagen S (see
figure 1) would allow retrofit in-situ. Alternatively, the
turbines could be dismantled, taken ashore and
retrofitted. The cost in labour and machine downtime
for this option would be exorbitant.
SAMs
The ability of SAMs to repel proteins and
polysaccharides is desirable, as the formation of
biofilms relies on such constituents. As biofouling is
a successive process, this would affect macro
foulers and invertebrates, and the ability to repel
cyprids has already been proven. The effectiveness
against all forms of biofouling is yet to proven – in a
marine environment SAMs would be exposed to a
diverse array of foulers. An antifouling solution must
cater for this; a SAM that exhibits excellent
antifouling properties to settlers with hydrophobic
adhesive is useless if it is colonized by foulers with
hydrophilic adhesive. For this reason, the use of
SAMs can be dismissed as a general solution for the
whole HATT assembly. I would suggest that SAMs
have the potential to be excellent anti-slime
coatings; slime is a thick biofilm, comprised of layers
of microbial scale foulers, which SAMs have been
shown to resist.
CONCLUSIONS
Microtopographies are effective at
providing antifouling for specific motile
spores.
Microtopographies may not be suited to
cope with the diverse array of fouling the
marine environment provides.
For the coating of large scale structures
with microtopographies to become
financially viable, an automated process
must be adopted.
Self-assembled monolayers lack the
versatility to perform well in the marine
environment.
7. 7 Adam Brann
FURTHER WORK
Investigation into the shear forces required to
remove fouling from topographical microstructures.
The effect of mechanical damage on the
antifouling efficacy of microtopographies.
Methods for automatically applying
microstructures to large scale
components
Investigation into the adhesion strength
of fouling organisms on
microtopographies, and ascertain a
critical foul release speed
Reducing cross axial drag at low flow
speeds using topographical
microstructures
ACKNOWLEDGEMENTS
I’d like to thank Ben Thomas for providing me with
an initial idea for this paper, and support throughout.
I’d also like to thank Adam Roberts for helping to
provide me with an initial direction.
REFERENCES
AkzoNobel., (2010). Antifouling performance at the
level you choose. Available:
http://www.international-
marine.com/literature/biocidalantifoulings-
whitepaper.pdf. Last accessed 23/11/2015.
AkzoNobel., (2013). History of fouling control.
Available: http://www.international-
marine.com/antifoulings/history-of-fouling-
control.aspx. Last accessed 18/11/2015.
AkzoNobel., (2014a). Fouling control explained.
Available: http://www.international-
marine.com/foulingcontrol/default.aspx. Last
accessed 20/11/2015.
AkzoNobel., (2014b). Controlled depletion
polymers. Available: http://www.international-
marine.com/antifoulings/controlled-depletion-
polymers.aspx. Last accessed 23/11/2015.
AkzoNobel., (2015a). Foul release properties.
Available: http://www.international-
marine.com/foulrelease/foul-release-
properties.aspx Last accessed 23/11/2015.
AkzoNobel., (2015b). Silicone. Available:
http://www.international-
marine.com/foulrelease/silicone.aspx. Last
accessed 07/12/2015.
Almukhtar, A., (2012). Effect of drag on the
performance for an efficient wind turbine blade
design. Energy Procedia. 18 (1), p.404 – 415.
AMBIO., (2010). The Biofouling Problem. Available:
http://www.birmingham.ac.uk/generic/ambio/about/
biofouling-problem.aspx. Last accessed 16/11/2015
ASM., (1985). ASM Metals Handbook. 9th ed. OH,
p12, Available:
http://products.asminternational.org/hbk/index.jsp
Athavale, S., (2010). Adhesion and adhesives
theory. Available:
http://www.slideshare.net/ashrikant58/05adhesion-
and-adhesives-theory. Last accessed 02/12/2015
Atlar, M., Callow, M., (2003). The development of
foul-release coatings for seagoing vessels. Journal
of Marine Design and Operations B, 4, 11.
Baier, R., (2006). Surface behaviour of
biomaterials: the theta surface for biocompatibility.
Journal of material science. 17 (11), p1057-1062.
Beech, I., Sunner, J., (2004). Biocorrosion: towards
understanding interactions between biofilms and
metals. Current Opinion in Biotechnology. 15 (1),
p181-186.
Beech, I., Bergel, A., Mollica, A., Flemming, H.,
Scotto, V., Sand, W., (2000). Simple methods for
the investigation of the role of biofilms in corrosion.
Biocorrosion. 00-02 (1), 1-5.
Berendsen, A.M., (1989). Contact matrix anti
fouling paints. In: TNO, CMO Marine painting
manual. Rotterdam: Springer-science and business
media. p.136.
Bers, A. V., Wahl, M., (2004). The influence of
natural surface microtopographies on fouling.
Biofouling, 20(1), 43-51.
Bressy, C., Margaillan, A., (2009). Tin free self-
polishing marine antifouling coatings. In: Hellio, C.
and Yebra, D. Advances in marine antifouling
coatings and technologies. Cambridge: Woodhead.
p445-456.
Bruijs, M., (2006). Pre-survey of marine fouling on
turbine support structures of the Offshore Windfarm
Egmond aan Zee. Biological Fouling. (1), p.5.
8. 8 Reducing the biofouling of tidal turbines using surface microstructures
Carman, M., Estes, T., Feinberg, A., Schumacher,
J., Wilkerson, W., Wilson, L., Callow, M., Callow, J.,
Brennan, A., (2006). Engineered antifouling
microtopographies – correlating wettability with cell
attachment. Biofouling. 22 , p11-21.
Candries, M., Anderson, C., Atlar, M., (2001) Foul
Release Systems and Drag. Last accessed:
27/11/15. Available:
http://www.paintsquare.com/library/articles/Foul_Re
lease_Systems_and_Drag__Observations_on_Ho
w_the_Coatings_Work.pdf
Cassie, A., Baxter, S., (1944). Wettability of porous
surfaces. Transactions of the Faraday Society. 40,
p546-551
Cavendish laboratory., (2013). Introduction to
microstructure. Available:
http://www.inference.phy.cam.ac.uk/prlw1/minp/Co
urseC/CP1.pdf. Last accessed 25/11/2015
Chambers, L.D., Stokes, K.R., Walsh, F.C., Wood,
R.J.K., (2006). Modern approaches to marine
antifouling coatings. Surface and coatings
technology. 201. p.3642–3652.
Chapman, R., G., Ostuni, E., Yan, L., & Whitesides,
G. M. (2000). Preparation of mixed self-assembled
monolayers (SAMs) that resist adsorption of
proteins using the reaction of amines with a SAM
that presents interchain carboxylic anhydride
groups. Langmuir, 16(17), 6927-6936.
Davey, M. E., O’Toole, G. A., (2000). Microbial
Biofilms: from Ecology to Molecular Genetics.
Microbiology and Molecular Biology Reviews,
64(4), p.850
Dennington, S., (2015). Understanding marine
fouling and assessing antifouling approaches.
Available:
https://connect.innovateuk.org/documents/2998699
/3676088/Simon+Dennington+Presentation.pdf/d8b
a85fe-a3ab-45b2-affc-aea0ef113749. Last
accessed 23/11/2015.
DFM Europe., (2009). Wind energy. Available:
http://dofilink.com/industries/windenergy. Last
accessed 05/12/2015.
Doyle, C., (2014). Gender bending snails recover
as toxic paint TBT is banned. Available:
http://www.abc.net.au/environment/articles/2014/01
/13/3916477.htm. Last accessed 01/12/2015.
European environmental bureau., (2014). Biocides.
Available:
http://risctox.istas.net/en/index.asp?idpagina=1192.
Last accessed 23/11/2015.
Ederth, T., Ekblad, T., Pettitt, M. E., Conlan, S. L.,
Du, C. X., Callow, M. E., Liedberg, B., (2011).
Resistance of galactoside-terminated alkanethiol
self-assembled monolayers to marine fouling
organisms. ACS applied materials &
interfaces, 3(10), 3890-3901.
EMEC., (2008). Tidal Devices. Available:
http://www.emec.org.uk/marine-energy/tidal-
devices/. Last accessed 03/12/2015.
Field, B., (1981). Marine Biofouling and its Control:
History and State-of-the-Art Review". In OCEANS
81. Boston, 16-18 September. Online: IEEE. p543-
543.
Finlay, J., Callow, M., Ista, L., Lopez, G., Callow, J.,
(2002). The Influence of Surface Wettability on the
Adhesion Strength of Settled Spores of the Green
Alga Enteromorpha and the Diatom Amphora.
Integrative and Comparative Biology. 42, p1116-
1122
Goodes, L.R., Wharton, J.A., Dennington, S.P.,
Stokes, K.R., (2014). Estimation of organic biocide
leaching rate using a modified cavity jump diffusion
model. Progress in Organic Coatings. 77, p1499-
1505.
Green rhino energy., (2015). Tidal stream energy.
Available:
http://www.greenrhinoenergy.com/renewable/marin
e/tidal_stream.php. Last accessed 09/12/2015.
Groenendijk, M., (2008). Fabrication of Super
Hydrophobic Surfaces by fs Laser Pulses. Laser
technik journal. 5, p44-47.
Grundke, K., Michel, S., Knispel, G., Grundler, A.,
(2008) Wettability of silicone and polyether
impression materials: Characterization by surface
tension and contact angle measurements. Colloids
and Surfaces A: Physicochemical and Engineering
Aspects. 317. p598-609
Gubisch, M., (2013). Aircraft paint suppliers explore
sharkskin coating. Available:
https://www.flightglobal.com/news/articles/aircraft-
paint-suppliers-explore-sharkskin-coating-381646/.
Last accessed 30/11/2015.
9. 9 Adam Brann
Hamm, J., Grow, B., Burn, B., Halland, C.,
Brennen, C., (2009). Book II. Essays and
miscellanies. 3. Question vii, About the fish called
Remora or Echeneis. Available:
http://www.gutenberg.org/files/3052/3052-h/3052-
h.htm Last accessed: 15/11/2015
Kiil, S., Yebra, D., (2009). Modelling the design and
optimization of chemically active marine antifouling
coatings. In: Hellio, C. and Yebra, D. Advances in
Marine Antifouling Coatings and Technologies.
Cambridge: Woodhead Publishing. p337-339.
Killea, L., (2014). Microbial community composition
of marine biofilms in a northern temperate. Open
Access Master's Theses. Paper 287. Available:
http://digitalcommons.uri.edu/theses/287
Laibinis, P. E., Whitesides, G. M., Allara, D. L., Tao,
Y. T., Parikh, A. N., & Nuzzo, R. G. (1991).
Comparison of the structures and wetting
properties of self-assembled monolayers of n-
alkanethiols on the coinage metal surfaces, copper,
silver, and gold. Journal of the American Chemical
Society, 113(19), 7152-7167.
Lee, W., Jin, M., Yoo, W., and Lee, J., (2004).
Nanostructuring of a Polymeric Substrate with Well-
Defined Nanometer-Scale Topography and
Tailored Surface Wettability. Langmuir. 20, p7665-
7669.
Li, B., Ye, Q., (2015). Antifouling Surfaces of Self-
assembled Thin Layer. In: Zhou, F. Antifouling
Surfaces and Materials. Berlin: Springer Berlin
Heidelberg. p31-54
Lin, F., Yanan, Z., Yingze,C., Xinxia,Y., Lei,J.,
(2011). The effect of surface microstructures and
surface compositions on the wettabilities of flower
petals. Soft Matter. 7, 2977-2980.
Lindholdt, A., Dam-Johansen, K., Olsen, S. M.,
Yebra, D., M. Kiil, S., (2015) Effects of biofouling
development on drag forces of hull coatings for
ocean-going ships: a review. Journal of Coatings
Technology and Research. (12) p415-444
Love, J. C., Estroff, L. A., Kriebel, J. K., Nuzzo, R.
G., & Whitesides, G. M. (2005). Self-assembled
monolayers of thiolates on metals as a form of
nanotechnology. Chemical reviews, 105(4), 1103-
1170.
Love, J. C., Wolfe, D. B., Haasch, R., Chabinyc, M.
L., Paul, K. E., Whitesides, G. M., & Nuzzo, R. G.
(2003). Formation and structure of self-assembled
monolayers of alkanethiolates on
palladium. Journal of the American Chemical
Society, 125(9), 2597-2609.
Lufthansa Technik., (2014). Shark meets
crane. Available: http://www.lufthansa-
technik.com/famos. Last accessed 03/02/2015.
Lufthansa Technik., (2015a). Highly automated
application process for innovative painting.
Available: http://www.lufthansa-technik.com/press-
releases-content/-
/asset_publisher/9Mf5/content/id/1527418. Last
accessed 30/11/2015.
Lufthansa Technik., (2015b). Highly automated
application process for innovative painting.
Available: http://www.lufthansa-technik.com/press-
releases-content/-
/asset_publisher/9Mf5/content/id/1527418. Last
accessed 30/11/2015.
Lynn, P., (2014). When waves meet WEC's.
In: Electricity from Wave and Tide An introduction
to marine energy. Chichester: John Wiley & Sons
Ltd.
Magin, C., Cooper, S., Brennan, A., (2010). Non-
toxic anti-fouling strategies. Materials Today. 13,
p36-44
Mahajan, S., 2010. Self-Assembled Nanostructures
[video, online]. Youtube. UCDavis. Available from:
https://www.youtube.com/watch?v=64z_n-OZDr4
Mann, E., Manna, D., Mettetal, M., May, R.,
Danemiller, E., Chung, K., Brennan, A., Reddy, S.,
Surface micropattern limits bacterial contamination.
Antimicrobial resistance and infection control;
3(1):28.
Mijle Meijer, H., (2009). Corrosion in offshore wind
energy. In The offshore wind power conference.
The Netherlands, February 12-13.
NNIN., (2015). The Water Race: Hydrophobic &
Hydrophilic Surfaces.Available:
http://www.nnin.org/sites/default/files/files/nnin1041
.pdf. Last accessed 09/12/2015.
Nugraha, R., Finlay, J. A., Hill, S., Fyrner, T., Yandi,
W., Callow, M. E., & Ederth, T. (2015). Antifouling
properties of oligo (lactose)-based self-assembled
monolayers. Biofouling, 31(1), p123-134.
Orme, J.A.C., Masters, I., and Griffiths, R.T.,
(2001) Investigation of the effect of biofouling on
10. 10 Reducing the biofouling of tidal turbines using surface microstructures
the efficiency of marine current turbines, in C.
French (ed.), Proc. MAREC 2001, (Institute of
Marine Engineers, 2001), 91-99 [ISBN 1-902536-
43-6]
Omae, I., (2003). Organotin anti-fouling paints and
their alternatives. Applied organometallic chemistry.
17, p81-105.
Pei, X. and Ye, Q., (2015). Development of marine
antifouling coatings. In: Zhou.F Antifouling surfaces
and materials. Berlin: Springer Berlin Heidelberg.
p135-151
PMSS., (2006). Environmental impact assessment
scoping report. Available:
https://tethys.pnnl.gov/sites/default/files/publication
s/Skerries_Scoping_Report_2006.pdf. Last
accessed 07/12/2015
Potter, M., Rose, N., (1996). Immunology of
Silicones. Berlin: Springer Berlin Heidelberg. p7.
Power-Technology., (2015). Strangford Lough Tidal
Turbine. Available: http://www.power-
technology.com/projects/strangford-lough/. Last
accessed 07/12/2015.
Rittschof, D., (2009). Novel Antifouling Coatings: A
Multiconceptual Approach. In: Flemming, H.,
Murthy, P., Venkatesan, R., Cooksey, K., Marine
and Industrial Biofouling. Berlin: Springer Berlin
Heidelberg. p179-187.
Rodriguez, I., (2012). Biomimetics as a tool for the
development of new materials. Available:
http://hellomaterialsblog.com/2012/08/22/biomimeti
cs-as-a-tool-for-the-development-of-new-materials/.
Last accessed 03/12/2015.
Schreiber, F., (2000). Structure and growth of self-
assembling monolayers. Progress in surface
science, 65(5), p151-257.
Schultz, M.P., Bendick, J.A., Holm, E.R., Hertel,
W.M., (2011). Economic impact of biofouling on a
naval surface ship. Biofouling. 27 (1), p.91.
Sea Generation Ltd., (2015). 'Welcome'. Available:
http://www.seageneration.co.uk/. Last accessed
03/12/2015.
Sewell, T., (2015). Biomimicry Shark
Denticles. Available: http://ocean.si.edu/ocean-
photos/biomimicry-shark-denticles. Last accessed
03/12/2015.
Sharklet., (2015). Products. Available:
http://sharklet.com/. Last accessed 02/12/2015.
Solomon, T., (2014). Proven Benefits from Foul
Release Coatings. In A. Yücel Odabaş Colloquium
Series (p. 79).
Taglietti, A., Arciola, C. R., D'Agostino, A., Dacarro,
G., Montanaro, L., Campoccia, D., ... & Visai, L.
(2014). Antibiofilm activity of a monolayer of silver
nanoparticles anchored to an amino-silanized glass
surface.Biomaterials, 35(6), p1779-1788.
Tidal Energy ltd. (2015). What is Tidal energy?.
Available:
http://www.tidalenergyltd.com/?page_id=1370. Last
accessed 20/11/2015.
Thielicke, W., (2015). Computer graphics of the
lotus affect. Available:
http://wthielicke.gmxhome.de/bionik/indexuk.htm.
Last accessed 03/12/2015.
Thorlaksen, P., Yebra, D., Català, P., (2010).
Hydrogel-based third generation fouling release
coatings. Last accessed:27/11/15. Available:
http://www.gallois.be/ggmagazine_2010/gg_05_09
_2010_218.pdf
Turner, A., (2010). Marine pollution from antifouling
paint particles. Marine Pollution Bulletin. 60 (2),
p159-171.
Turnock, S.R., Nicholls-Lee, R., Wood, R.J.K., and
Wharton, J.A., (2009) Tidal turbines that survive?
In, Marine Corrosion Forum, Birmingham, UK, 08
Jul 2009. Available:
http://eprints.soton.ac.uk/66727/1/Gold_platedv4.pd
f
UK Gov., (2012). Electricity market reform: policy
overview . Available:
https://www.gov.uk/government/uploads/system/upl
oads/attachment_data/file/48371/5349-electricity-
market-reform-policy-overview.pdf. Last accessed
20/11/2015.
UK Gov., (2014). Delivering UK Energy
Investment. Available:
https://www.gov.uk/government/uploads/system/upl
oads/attachment_data/file/331071/DECC_Energy_I
nvestment_Report.pdf. p.53. Last accessed
20/11/2015
UK Gov., (2015). Energy Trends - Section 6. Chart
6.2, p.44. Available:
11. 11 Adam Brann
https://www.gov.uk/government/uploads/system/upl
oads/attachment_data/file/466478/Renewables.pdf
UK Gov., (2011). Planning our electric future: a
White Paper for secure, affordable and low‑carbon
electricity. (2.1.17), p.31. Available:
https://www.gov.uk/government/uploads/system/upl
oads/attachment_data/file/48129/2176-emr-white-
paper.pdf. Last accessed 20/11/15
Walker, J., Flack, K., Lust, E., Schultz, M., Luznik,
L., (2014). Experimental and numerical studies of
blade roughness and fouling on marine current
turbine performance. Renewable Energy. 66 (4.3),
p266
Wen, L., Weaver, J., Lauder, G., (2014).
Biomimetic shark skin: design, fabrication and
hydrodynamic function. Journal of experimental
biology. 217. p1656-1666. Available:
http://jeb.biologists.org/content/jexbio/217/10/1656.f
ull.pdf
Wenzel, R., (1936). Resistance of solid surfaces to
wetting by water. Industrial & Engineering
Chemistry. 28, p988-994.
Zhang, X., Zhong, X., Meng, X., Yi, G., & Jia, J.
(2012). Adhesion and friction studies of nano-
textured surfaces produced by self-assembling Au
nanoparticles on silicon wafers. Tribology Letters,
46(1), p65-73.