Months Of Immersion Research Articles

Early colonization of sessile megabenthos on electrolytic carbonated structures (Alicante's harbor, Western Mediterranean)

Biofouling of different artificial substrates was studied to determine the differences in biofouling assemblages among different substrates. However, studies on biofouling on natural substrates like electrolytic carbonated ones are lacking. These substrates have a great potential for coral reef restoration in tropical areas and for biofilter construction. Thus, this study was developed to examine the colonization of sessile macrofouling in the port of Alicante (SE Spain, Western Mediterranean) on two types of substrates: electrolytic carbonated and bare steel (as control) over three months of immersion (October 2019–January 2020). The community diversity was studied through different biotic parameters and abundance of assemblages, and preference of organisms according to their status and functional group (active filter feeders). Univariate and multivariate analyses (PERMANOVA and SIMPER) were also applied to examine the differences between carbonate and control substrates. The carbonated substrate had a more structured community and higher abundance, recruitment, and diversity indexes than the bare steel. Moreover, filter feeders (Porifera, Bivalvia, and Ascidiacea) were more abundant, and most of them only appeared in the carbonated substrate. These results show the potential of carbonated structures as biofilters.

Fishers’ Cultural Funds of Knowledge and Translanguaging Praxis for the Development of Contextualized Instructional Material: A Narrative Ethnography

The implementation of K to 12 curriculum in coastal villages in the Philippines posed a pressing concern on the dearth of contextualized instructional materials (IM). This study aimed to generate the cultural funds of knowledge and translanguaging praxis of migrant fishers as bases for the development of contextualized IM. Under the lens of narrative ethnography, knowledge, beliefs, and practices of migrant fishers were documented in memory bank charts from six months of immersion in the coastal villages. Translingual narratives of purposively chosen participants were analyzed in the QDA Lite Miner software. Three translingual storybooks and teacher’s guides were developed, validated, evaluated, and pilot tested. It resulted to “very acceptable” for the storybooks and “excellent” rating for the teacher’s guides. The study recommends that school heads, teachers, and parents in the coastal villages may interact beyond the classroom setting and their indigenous knowledge will be used in the development of IM.

Long-lasting biofouling formation on transparent fouling-release coatings for the construction of efficient closed photobioreactors

In order to build an efficient closed-photobioreactor (PBR) in which biofouling formation is avoided, a non-toxic coating with high transparency is required, which can be applied to the interior surface of the PBR walls. Nowadays, amphiphilic copolymers are being used to inhibit microorganism adhesion, so poly(dimethylsiloxane)-based coatings mixed with poly(ethylene glycol)-based copolymers could be a good option. The 7 poly(dimethylsiloxane)-based coatings tested in this work contained 4% w/w of poly(ethylene glycol)-based copolymers. All were a good alternative to glass because they presented lower cell adhesion. However, the DBE-311 copolymer proved the best option due to its very low cell adhesion and high transmittance. Furthermore, XDLVO theory indicates that these coatings should have no cell adhesion at time 0 since they create a very high-energy barrier that microalgae cells cannot overcome. Nevertheless, this theory also shows that their surface properties change over time, making cell adhesion possible on all coatings after 8 months of immersion. The theory is useful in explaining the interaction forces between the surface and microalgae cells at any moment in time, but it should be complemented with models to predict the conditioning film formation and the contribution of the PBR’s fluid dynamics over time.

The Effect of Shipbuilding Material Type on Biofouling Growth at Boom Marina, Banyuwangi, East Java, Indonesia

ABSTRACTThe presence of biofouling has an impact on the ship’s performance, which is reduced to require more fuel, in the end, it contributes significantly to cost increases. Biofilms provide a suitable substrate for the growth of microorganisms. Ship hull as a substrate for biofilms has many kinds of material. Steel, wood, laminated bamboo, and fiber are often used for ship hulls. Different material makes different characteristics of substrate for biofilms. The aim of this research is to determine the growth rate of biofouling in each shipbuilding material and to find out which vessel material is suitable for use in the Bali Strait. The experiment was located in Boom Marina, Banyuwangi. The materials used in this research are wood, laminated bamboo, and fiber. The daily growth rate (DGR) is calculated every week of observation. Wood had the most biofouling with a DGR of 2,646 g/day. Laminated bamboo had the least biofouling in this research after 2 months of immersion with a DGR of 0,086 g/day. Keywords: Biofouling, shipbuilding material, daily growth rate.

Indentation, finite element modeling and artificial neural network studies on mechanical behavior of GFRP composites in an acidic environment

In this study, the indentation tests are performed with various forces using the Vickers indenter to investigate the mechanical properties, including the elastic modulus, hardness, and the plasticity index of pure, and incorporated glass fiber reinforced polymer (GFRP) composites with nanosilica and nanoclay. To study the effect of adding different nanoparticles on reducing the mechanical properties of immersed specimens in acid for 0, 1 and 3 months, incorporated composite specimens with 3 wt percent (wt. %) of nanoparticles were fabricated using hand lay-up method. Accordingly, the reduction in mechanical properties and increase in plasticity index was attributed to the penetration of acid into composite specimens during the immersion period, which resulted in the failure of matrix and fiber following increased moisture penetration. Adding the nanoparticles especially nanoclay, has alleviated the trend of drop in mechanical properties. In fact, for the incorporated composite specimen with nanoclay, the hardness and elastic modulus of the immersed samples in acid for 0 and 3 months indicated a decrease of 10.55 and 7.88%, respectively on grounds of hydrophobic nature of nanoclay. Conversely, incorporating nanosilica increased the plasticity index leading to higher rate of degradation, which was even more than pure sample, yet the pure sample had the lowest mechanical properties after 3 months of immersion. In addition, Finite element modeling (FEM) and artificial neural network (ANN) were used to respectively predict the indentation behavior of fabricated composite specimens and study the effects of immersion time in an acidic environment.

Immersion Time Determines Performance of Artificial Habitats in Commercial Harbours by Changing Biodiversity of Colonising Invertebrate Assemblages

In highly modified coastal environments, such as commercial harbours, the installation of artificial habitats has garnered support as a means of enhancing local biological recruitment and connectivity. The success of these measures depends largely on the patterns of species colonisation. Using post-installation monitoring data, we compared the composition of assemblages of invertebrates colonising artificial habitats that were immersed for different periods (~6 vs. ~18 months) in three commercial harbours along the French Mediterranean coast. The artificial habitats were colonised by taxonomically diverse invertebrate assemblages of ecological and economic importance, including molluscs, crustaceans, and echinoids. Composition differed significantly with the immersion time of the artificial habitats, with total abundance, species richness, and evenness being significantly higher after ~18 than after ~6 months of immersion, indicating that long periods are necessary to enrich these new habitats with economically and ecologically important species. These results can inform restoration protocols and emphasise the value of post-installation monitoring programs.

Color Stability of Nanoparticles-Modified Dental Resin-Based Composites

To evaluate the effect of beverages (coffee, tea, Cola-Cola, and mineral water) on the color stability of resin-based composite (RBC) materials modified with different nanoparticles (NPs). The specimens (70/beverage) were fabricated from light-cured RBCs and divided according to NPs into four groups: one control, unmodified (N0); and three experimental—ZrO2 (Zr), TiO2 (Ti), and SiO2 (Si) groups. Each experimental group was further subdivided into two subgroups according to NP concentrations: 3 wt.% and 7 wt.% (n = 10). A spectrophotometer was used to assess the color change (∆E) before and after six months of immersion. Data were analyzed and compared using one-way-ANOVA followed by Bonferroni’s post-hoc test (α = 0.05) and subsequently ∆E value conversion to National Bureau of Standards (NBS) units. The modified light-cured RBCs with ZrO2, TiO2, and SiO2 demonstrated smaller color changes after immersion in the beverages than the unmodified group (p < 0.001). Zr groups showed the lowest ΔE, followed by Ti and Si groups; a 3% concentration resulted in a lower mean ΔE than the 7% concentration. NBS findings showed that coffee and tea produced marked unacceptable color changes (NBS units were >3), and Coca-Cola resulted in noticeable color changes (NBS units between 1.5 and 3), while water produced slight color changes (NBS ≤ 1). Modification of RBCs with both concentrations of ZrO2, as well as 3% of TiO2 and SiO2, may improve its color stability. Based on NBS results, RBCs immersed in mineral water and Coca-Cola showed clinically acceptable color changes, while those immersed in coffee and tea were clinically unacceptable.

Development of a Surface Treatment to Achieve Long-Lasting Antimicrobial Properties and Non-Cytotoxicity through Simultaneous Incorporation of Ag and Zn via Two-Step Micro-Arc Oxidation

A customized micro-arc oxidation (MAO) treatment technique was developed to obtain antibacterial properties with no toxicity on Ti surfaces. A two-step MAO treatment was used to fabricate a specimen containing both Ag and Zn in its surface oxide layer, and the optimal incorporation conditions were determined. Surface characterization by EDS was performed followed by the antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) and osteogenic cell compatibility evaluations. In addition, metal ion release tests were performed to evaluate the contents of Ag and Zn and the ion release behavior in order to simulate practical usage. MAO-treated specimens prepared using proper concentrations of Ag and Zn (0.5Ag-5Zn: 0.5 mM AgNO3 and 5.0 mM ZnCl, respectively) exhibited excellent antibacterial properties against E. coli and S. aureus and no toxicity to MC3T3-E1 in antibacterial and cytotoxic evaluations, respectively. The antibacterial property of 0.5Ag-5Zn against S. aureus was sustained even after two months of immersion in physiological saline, simulating the in vivo environment.

Ultra-robust icephobic coatings with high toughness, strong substrate adhesion and self-healing capability

Enabling surfaces with passive anti-icing properties is an emerging, facile, economical, and energy-saving strategy to mitigate the harm caused by ice accretion. However, the combination of icephobicity and robustness remains a daunting challenge. Herein, we present an ultra-robust transparent icephobic coating with high toughness, strong substrate adhesion, and self-healing capability. Hydrophobicity, smoothness, and softness of the coating guarantee low ice adhesion strength. By incorporating a spongy structure, the ice adhesion strength of the coating is lowered further down to 26.7 ± 1.1 kPa. Importantly, the coating exhibits high toughness, strong adhesion to the substrate, and self-healing capability due to the presence of multiple hydrogen bonding. Consequently, the coating maintains its icephobicity after 35 icing/deicing cycles and 600 abrasion cycles, is resilient to delamination, and is able to heal and recover its icephobicity from the mechanical damage introduced by both cuts and abrasions. Moreover, the coating sustains its icephobicity after eight months of immersion in saltwater, as well as exposure to the near-arctic weather in Trondheim (Norway). This work presents new insights into the design of robust icephobic coatings that can sustain severe mechanical loading for use in real complex environments.

Polyhexamethylene guanidine molybdate as an efficient antibacterial filler in epoxy coating for inhibiting sulfate reducing bacteria biofilm

Readily synthesized and highly antibacterial polyhexamethylene guanidine molybdate (PHMG-MoO4) can be used as a filler to greatly improve the resistance of epoxy coating to sulfate reducing bacteria (SRB) biofilm. In SRB inoculated medium, no SRB biofilm formed on PHMG-MoO4/epoxy coating after 120 days, and the corrosion current density of the epoxy coating painted carbon steel decreased by 99.0 % after addition of PHMG-MoO4 in the coating. There were also fewer fouling organisms on PHMG-MoO4/epoxy coating after 4 months of immersion in the actual seawater. The PHMG-MoO4 with low water solubility can remain in epoxy coating for a long time and therefore effectively and continuously inhibited the bacteria on the coating.

Microbial Biofilms Colonizing Plastic Substrates in the Ross Sea (Antarctica)

Very few studies have investigated marine microbial colonization in polar regions, but climate-changing scenarios stress the importance of these investigations to protect life in such extremely vulnerable ecosystems. In two different coastal sites of the Ross Sea (Road and Tethys Bays, Antarctica) exposed to different stressors, the microbial biofilm colonizing the surface of plastic (polyvinyl chloride, PVC, and polyethylene, PE) panels left submerged in two experiments at different timescales (“short-term”: 3 months, and “long-term”: 9 and 12 months) was studied. The abundance and metabolic enzymatic activities [leucine aminopeptidase (LAP), beta-glucosidase (GLU) and alkaline phosphatase (AP)] of the prokaryotes and the microalgal abundance and species composition were analyzed, in parallel with the main environmental parameters. The prokaryotic community showed higher abundance and metabolic activities on PVC than on PE as opposed to microalgae. A peak in the microfouling prokaryotic abundance and metabolic functions was frequently recorded after 3 months of immersion, corresponding to the late austral summer period. LAP and AP were the most active enzymes, suggesting that microbial metabolic profiles were modulated by labile organic substrates. Our results suggest that the composition and function of microbial biofilm could be considered as sentinels of natural or anthropic-related disturbances.

The plate collector, a new option for Pinctada margaritifera spat collection in French Polynesia

The aquaculture industry can constitute an important source of waste in the environment. In atoll lagoons of French Polynesia, among the materials used by pearl farmers, shade-mesh collectors can release toxic substances and are responsible of microplastics production. With the aim of providing a less polluting alternative, we performed in situ tests comparing reusable plate collectors and shade-mesh collectors during 16 months. Plate collectors were significantly more efficient for spat collection, especially after the first 6 months of immersion (P < 0.0001). These results confirmed that this device can be a suitable and more sustainable alternative for the pearl industry.

A Degradation Study of Poly(3‐Hydroxybutyrate‐Co‐3‐Hydroxyvalerate) and Olive Husk Flour Biocomposites Under Marine Environment

AbstractIn this work, the main objective is to investigate the effect of olive husk flour (OHF) used as a biofiller on the marine degradation of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) biocomposites up to 6 months of immersion in sea water at 25°C and 40°C. Film samples based on neat PHBV and PHBV are filled with 20 wt.% OHF is prepared by melt compounding. After 6 months of immersion in sea water, the study reveals a noticeable decrease in the absorption band intensity of ester groups of PHBV through Fourier transform infrared (FTIR‐ATR) spectroscopy, even more in the presence of OHF in PHBV biocomposite due to hydrolytic degradation. This phenomenon is, however, more pronounced at 40°C. This also agrees with differential scanning calorimetry (DSC) data, which indicates a large increase in crystallinity index (Xc) resulting from short chains reorganization. Moreover, scanning electron microscopic (SEM) analysis shows for both degraded samples, eroded and cracked surfaces, being however more pronounced for PHBV/OHF biocomposite at 40°C. This study highlights the role of OHF as a promotor of marine degradation of PHBV.

On the Properties Evolution of Eco-Material Dedicated to Manufacturing Artificial Reef via 3D Printing: Long-Term Interactions of Cementitious Materials in the Marine Environment

This paper deals with the evolution monitoring of biomass colonization and mechanical properties of 3D printed eco-materials/mortars immersed in the sea. Measurements of tensile strength, compressive strength, and Young’s modulus were determined on samples deployed along the Atlantic coast of Europe, in France, United Kingdom, Spain, and Portugal. The samples were manufactured using 3D printing, where six mix designs with a low environmental impact binder were used. These mortars were based on geopolymer and cementitious binders (Cement CEM III), in which sand is replaced by three types of recycled sand, including glass, seashell, and limestone by 30%, 50%, and 100% respectively. The colonization of concrete samples by micro/macro-organisms and their durability were also evaluated after 1, 3, 6, 12, and 24 months of immersion. The results showed that both biomass colonization and mechanical properties were better with CEM III compared to geopolymer-based compositions. Therefore, the mixed design optimized according to mechanical properties show that the use of CEM III should be preferred over these geopolymer binders in 3D printed concrete for artificial reef applications.

Development of laboratory tests to measure the growth kinetic of micro-algae of concrete in marine environment and comparison to in-situ experiments

Climate change associated with population growth drive the building sector’s innovation in developing new ecological and sustainable concrete solutions. Regarding marine environment the rise of sea level is a main concern for several big cities across the world. New sea defense infrastructure around cities is expected to rise in the coming years. This will not be possible and accepted without any ecological compensation and thus by developing new ecological concrete range. The development of Bio-active concrete is one part of the solution: in addition to their conventional structural performance, these concrete promote marine bio-fouling and biodiversity. To reach this objective, a laboratory test was developed to screen different concrete surfaces and compositions. The bio-receptivity capacity of a concrete surface is measured by the amount of micro-algae on the concrete surface after four weeks test. This quick lab test supported the development of a new range of concretes called Bi-Layer porous concrete made up of one structural layer and one highly porous bio-active layer. These concrete were implemented as quay walls and reefs in Mediterranean and Atlantic sea. Very promising results were obtained after 18 months of immersion regarding bio-fouling activity and micro-algae diversity on the concrete confirming the results given by the laboratory test.

Highly protective polyolefin coating modified with ceria nano particles treated with N,N,N',N'-Tetrakis(2-hydroxyethyl)ethylenediamine for corrosion protection of carbon steel

A polyolefin coating was modified with cerium oxide nanoparticles treated with N,N,N',N'-Tetrakis(2-hydroxyethyl)ethylenediamine (THEEDA) as corrosion inhibitor for corrosion protection of carbon steel. Electrochemical Impedance Spectroscopy tests carried out in 0.05 M NaCl revealed low-frequency impedance modulus around 1012 Ω cm2 for the modified coating without significant changes after three months of immersion. The self-healing ability of modified coating was studied by combining different localized electrochemical techniques, namely localized impedance spectroscopy (LEIS), the scanning vibrating electrode technique (SVET), and scanning fiber-optic dissolved oxygen microsensor. This comprehensive study confirmed the ability of ceria nanoparticles treated with THEEDA to mitigate corrosion thanks to the synergistic protective role of ceria nanoparticles and THEEDA that inhibit both cathodic and anodic activities, respectively.

What governs marine fouling assemblages on chemically-active antifouling coatings?

From an environmental perspective, there is a need to reduce the amount of biocides in chemically-active antifouling (AF) coatings, as these biocides can cause severe damage to marine life. In this study, six active molecules known as booster biocides were added at 3 wt% in solvent and aqueous-based acrylic paints. DCOIT, dichlofluanid, zinc pyrithione, copper pyrithione, tralopyril and zineb were used alone and mixed with a lower amount of copper (I) oxide and copper thiocyanate (10 wt%) than is currently used or with zinc oxide fillers. Field immersion tests were carried out in the Atlantic Ocean (Ste Anne du Portzic) and the Mediterranean Sea (Toulon), with contrasting physicochemical properties of water and macrofoulers' biodiversity. Microscopic analyses showed that AF coatings reduced the bacterial density differently for short immersion times at Ste Anne du Portzic. After four/five months of immersion, results, including multidimensional analyses, showed first specific patterns in the macrofoulers' assemblages depending on the site. In addition, the structure of macrofoulers' assemblages was affected by the biocide itself and by the combination of the biocide and the binder. When efficient, AF coatings appeared to decrease the richness with a strongest effect at Toulon. DCOIT was the most performing booster biocides whatever the immersion site and the polymer binder used. DCOIT was found to be efficient against marine bacteria and macrofoulers at Ste Anne du Portzic. The combination of zinc pyrithione with ZnO fillers in an aqueous-based AF paints exhibited the highest activity in the Mediterranean Sea over 16 months of immersion.

Durability and chemical resistance of nanoparticles fly ash and silica fume belite cement pastes against sulfate and chloride aggressive media- Part II

The durability (chemical resistence) of the Portland cement (OPC), belite cement (BC) and the optimum belite cement (B4), which their physical and chemo/mechanical properties were perviously investigated in Part I, against 4 % MgSO4 and 4% MgCl2 solutions up to 12 months in terms of compressive strength, total sulfate and total chloride was evaluated and studied. Results showed that the optimum belite cement (B4) containing 15 % High pulverized fly ash (HPFA) and 5 % Silica fume (SF) could be resisted up to 6 months, while that of BC could be withstood only up to 5 months, and the OPC could not resist more than three months of immersion in 4% MgSO4 solution. The compressive strength values exhibited by the samples immesed in sulfate solution at 3, 5 and 6 months of immersion were 83.81, 76.38 and 91.13 MPa, respectively. The same trend was displayed when the same samples were exposed to 4% MgCl2 solution. The compressive strength values exhibited by the same samples exposed to chloride solution at 3, 5 and 6 months of immersion were 84.49, 82.23 and 93.32 MPa, respectively. The total sulfate and chloride contents were enhanced with immesion time up to 12 months, but their values were the minimum with B4 and the maximum with OPC, while with BC were the medium. The optimum cement batch (B4) achieved the highest resistance where it recorded the lowest values for sulfate and chloride ions, but the OPC exhibited the lowest resistance where it recorded the highest values of sulfate and chloride contents at all immersion ages till 12 months.

Efficacy testing of novel antifouling systems for marine sensors

Marine sensors are widely employed tools for remotely providing a representation of their environment. The primary factor limiting measurement accuracy and deployment longevity is biofouling. For prevention, copper is the most widely applied biocide, often in form of adhesive copper tapes. However, for complex shapes these tapes are challenging to apply. Furthermore, sensor operating life frequently exceeds the antifouling protective period of the tape and the exchange of antifouling systems can be prohibitively time consuming and expensive. Alternative antifouling systems are needed to improve the cost-effectiveness of marine monitoring.This study tested a novel adhesive antifouling film based on copper cold spray technology in two concentrations (586 g m−2 and 306 g m−2) against a commercial copper tape (367 g m−2) and an uncoated control. After ten months of immersion, the lower concentration adhesive film performed equal to the commercial copper tape while achieving higher durability and better leaching control. In contrast, the antifouling performance of the high-concentration film was at times lower than that of the commercial copper tape, likely due to high embedment depth of copper particles. Customizable, cold spray metallised adhesive films may offer an advantage compared to ‘traditional’ tapes, including the potential to reduce copper emissions.

Effect of nanoparticles on the improving mechanical behavior of GFRP composites in a corrosive environment

Corrosive environment can significantly effect on the mechanical behavior of composite structures which can improve by using hydrophobic nanoparticles. The aim of this study is to investigate the improvement of the mechanical properties of incorporated glass fiber reinforced polymer (GFRP) composite specimens with 3 wt. % of nanoclay and nanosilica in a corrosive environment. Filled GFRP composites were fabricated using the mechanical stirrer following by sonication method, and the hand layup method. After preparing the neat and incorporated GFRP according to ASTM standards, all the samples were immersed in 5% sulfuric acid solution for 0, 1, and 3 months. As the immersion time increased, the samples containing nanosilica absorbed more water than the other samples. The tensile and compressive tests were performed at different immersion times to obtain the ultimate tensile and compressive strength and tensile modulus. The results showed that by adding nanoparticles, the mechanical properties were increased, which GFRP containing nanoclay showed a better behavior in the corrosive environment. By adding 3 wt. % of nanoclay, the ultimate tensile and compressive strength and the tensile modulus decreased after one month of immersion by only 0.34%, 1.81% and 2.95%, respectively, and after three months of immersion only decreased by 0.43%, 10.88% and 6.95%, respectively. Finally, SEM images of all specimens were examined to investigate the fracture mechanisms and the corrosion behavior of fabricated nanocomposites.