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Recent Submissions

  • Monitoring residual fouling after cleaning of multi-fiber membrane modules fiber-by-fiber using non-invasive MRI monitoring

    Yan, Bin; Blankert, Bastiaan; Vogt, Sarah J.; Vrouwenvelder, Johannes S.; Johns, Michael L.; Fridjonsson, Einar O. (Water Research, Elsevier BV, 2022-11-25) [Article]
    In this study non-invasive low field magnetic resonance imaging (MRI) technology was used to monitor fouling induced changes in fiber-by-fiber hydrodynamics inside a multi-fiber hollow fiber membrane module containing 401 fibers. Using structural and velocity images the fouling evolution of these membrane modules were shown to exhibit distinct trends in fiber-by-fiber volumetric flow, with increasing fouling causing a decrease in the number of flow active fibers. This study shows that the fouling rate is not evenly distributed over the parallel fibers, which results in a broadening of the fiber to fiber flowrate distribution. During cleaning, this distribution is initially broadened further, as relatively clean fibers are cleaned more rapidly compared to clogged fibers. By tracking the volumetric flow rate of individual fibers inside the modules during the fouling-cleaning cycle it was possible to observe a fouling memory-like effect with residual fouling occurring preferentially at the outer edge of the fiber bundle during repeated fouling-cleaning cycle. These results demonstrate the ability of MRI velocity imaging to quantitatively monitor these effects which are important when testing the effectiveness of cleaning protocols due to the long term effect that residual fouling and memory-like effect may have on the operation of membrane modules.
  • Contrasting genetic diversity and structure between endemic and widespread damselfishes are related to differing adaptive strategies

    Robitzch Sierra, Vanessa S. N.; Saenz-Agudelo, Pablo; Alpermann, Tilman J.; Frédérich, Bruno; Berumen, Michael L. (Journal of Biogeography, Wiley, 2022-11-24) [Article]
    Aim Several marine biogeographical provinces meet at the Arabian Peninsula. Where and how these junctions affect species is poorly understood. We herein aimed to identify the barriers to dispersal and how these shape fish populations, leading to differing biogeographies despite shared habitat and co-ancestry. Taxon Dascyllus marginatus (endemic) and Dascyllus abudafur (widespread). Location Coral reefs from the Red Sea (RS), Djibouti, Yemen, Oman, and Madagascar. Methods We tested potential barriers to gene flow using RADseq-derived SNPs and identified whether population genetic differences on each side of these barriers were neutral or selective to relate this to the biogeography of the species. Seven locations (ranging over 5100 km) were sampled for the endemic and six (ranging over 7400 km) for the widespread species, taking 20 individuals per location, with two exceptions. Results Dascyllus marginatus populations (comprising 5648 SNPs) had an order of magnitude higher genetic differentiation compared to D. abudafur (comprising 10,667 SNPs), as well as several outlier loci that were absent in D. abudafur despite equal sampling locations. In both species, the RS and Djibouti specimens formed one genetic cluster separated from all other locations. Although ranging from the RS to Madagascar, D. abudafur was absent in Yemen and Oman. Main Conclusions Stronger genetic structure at smaller geographical scales and outlier loci in the endemic species seem associated with faster adaptation to environmental differences and selective pressure. Genetic differentiation in the widespread species is neutral and only occurs at large geographical distances. Restrictive transitions (between the Gulf of Aqaba and the RS or the RS and the Gulf of Aden) do not hinder gene flow in either species, and the environmental shift within the RS (at 22°N/20°N) only affected the endemic species. The genetic break in the Gulf of Aden likely reflects historical colonization processes and not contemporary environmental regimes.
  • Understanding the effect of membrane interfacial wetting properties on membrane distillation flux

    Jin, Yong; Ghaffour, NorEddine (Desalination, Elsevier BV, 2022-11-24) [Article]
    Membrane distillation (MD) is promising for many applications such as seawater desalination. Designing membranes with high vapor flux is preferred to achieve high efficiency. However, understanding of effects of the membrane interfacial wetting properties on the vapor flux in MD is still missing. Here, elucidating this effect by theoretical and experimental tools is presented. Three interfacial wetting properties are identified, namely slip vs. non-slip, wetting vs. non-wetting and rough evaporation interface. While superhydrophobic surfaces of the membrane offer slippage of fluid, the effect of the slip condition has little effect on the heat and mass transfer in MD due to the relatively small slip length. When the fluid penetrates into and wets the membrane, the vapor flux increases due to the shortened vapor transport distance although the stagnant penetration layer hinders heat transfer. The rough evaporation interface with increased evaporation area does not necessarily significantly increase vapor flux. The rough evaporation problem can be reduced to an equivalent partial wetting problem with a certain wetting depth. This work clarifies the role of membrane interfacial wetting properties in vapor flux variation, which provides guidance for future membrane interfacial design to enhance vapor flux in MD.
  • Long-term performance of a hybrid indirect evaporative cooling-mechanical vapor compression cycle: A case study in Saudi Arabia

    Chen, Qian; M, Kum Ja; Burhan, Muhammad; Shahzad, Muhammad Wakil; Ybyraiymkul, Doskhan; Oh, Seungjin; Cui, Xin; Ng, Kim Choon (Frontiers in Built Environment, Frontiers Media SA, 2022-11-08) [Article]
    In Saudi Arabia, air conditioning is the main consumer of electricity, and increasing its energy efficiency is of great importance for energy conservation and carbon footprint reduction. This study presents the evaluation of a hybrid indirect evaporative cooling-mechanical vapor compression (IEC-MVC) cycle for cooling applications in Saudi Arabia. Most cities in this country are characterized by a high sensible cooling demand, and a few cities near the coasts of the Red sea and the Persian Gulf also need dehumidification. By employing the hybrid system, IEC can undertake about 60% of the cooling load in the summer of arid cities, and energy consumption can be reduced by up to 50%. The contribution of IEC and energy saving are less significant in humid cities because the latent loads have to be handled by MVC. Over the whole year, IEC contributes 50% of the total cooling capacity and reduces energy consumption by 40% in dry cities, while the saving is lower at 15%–25% in humid cities like Mecca and Jeddah. The average water consumption of the IEC is in the range of 4–12 L/hr. The water consumption can be replenished by the condensate collected from the MVC evaporator if the ambient humidity is high. Based on the annual performance, the cost of the IEC-MVC process is calculated, and it is 15%–35% lower than the standalone MVC. The results demonstrate the great potential of the hybrid IEC-MVC cycle in Saudi Arabia.
  • Computational fluid dynamics modelling of air-gap membrane distillation: Spacer-filled and solar-assisted modules

    Ansari, Abolfazl; Galogahi, Fariba Malekpour; Millar, Graeme; Helfer, Fernanda; Thiel, David V.; Soukane, Sofiane; Ghaffour, NorEddine (Desalination, Elsevier BV, 2022-11-05) [Article]
    Air-gap membrane distillation (AGMD) is a novel method of water purification and promises to reduce heat requirements. However, AGMD is characterized by low water permeate flux and a significant downstream performance reduction including temperature, concentration polarisations and membrane fouling. These challenges are difficult to explore both experimentally and numerically. To date, computational fluid dynamics (CFD) of AGMD focuses on temperature polarisation without considering solute transport. In addition, they lacked an accurate calculation of water flux affecting the distributed flow properties, especially close to the membrane. A 2D comprehensive study using CFD simulation of the AGMD was developed to determine the effectiveness of solar absorbers and spacer filaments on these challenges. A precise logarithmic function of vapour pressure was used to model the mass transfer within the membrane. The simulation was in excellent agreement with previously published experimental results. Results showed that using solar absorbers can slightly increase the water flux and decrease both the temperature and concentration polarisation effects. Additionally, the results were more sensitive to the air-gap thickness compared to using solar absorbers. Results also proved that cylindrical detached spacers provided higher water flux when compared to semicircular and rectangular attached spacers. The proposed spacer-filled module improved the AGMD performance and resulted in the uniform water flux from the inlet to the outlet. The water flux increased by 15 %, and the downstream performance variation of the developed module was <3 % throughout the module, compared to 21 % for the module with no spacer. This is a very encouraging development for low-energy water purification systems.
  • Molecular phenotyping uncovers differences in basic housekeeping functions among closely related species of hares (Lepus spp., Lagomorpha: Leporidae)

    Gaertner, Kateryna; Michell, Craig; Tapanainen, Riikka; Goffart, Steffi; Saari, Sina; Soininmäki, Manu; Dufour, Eric; Pohjoismäki, Jaakko L. O. (Molecular Ecology, Wiley, 2022-11-01) [Article]
    Speciation is a fundamental evolutionary process, which results in genetic differentiation of populations and manifests as discrete morphological, physiological and behavioral differences. Each species has travelled its own evolutionary trajectory, influenced by random drift and driven by various types of natural selection, making the association of genetic differences between the species with the phenotypic differences extremely complex to dissect. In the present study, we have used an in vitro model to analyze in depth the genetic and gene regulation differences between fibroblasts of two closely related mammals, the arctic/subarctic mountain hare (Lepus timidus Linnaeus) and the temperate steppe-climate adapted brown hare (Lepus europaeus Pallas). We discovered the existence of a species-specific expression pattern of 1,623 genes, manifesting in differences in cell growth, cell cycle control, respiration, and metabolism. Interspecific differences in the housekeeping functions of fibroblast cells suggest that speciation acts on fundamental cellular processes, even in these two interfertile species. Our results help to understand the molecular constituents of a species difference on a cellular level, which could contribute to the maintenance of the species boundary.
  • First records of two large pelagic fishes in the Red Sea: wahoo (Acanthocybium solandri) and striped marlin (Kajikia audax)

    Williams, Collin T.; Arostegui, Martin C.; Braun, Camrin D.; Gaube, Peter; Shriem, Marwan; Berumen, Michael L. (Journal of the Marine Biological Association of the United Kingdom, Cambridge University Press (CUP), 2022-11-01) [Article]
    This report provides the first confirmed identifications of wahoo (Acanthocybium solandri) and striped marlin (Kajikia audax) in the Red Sea, expanding the known ranges of these species into the basin. Potential mechanisms responsible for the lack of regional documentation of the two species are further discussed. These findings illustrate the need for systematic biodiversity surveys of pelagic fish assemblages in the Red Sea.
  • Effects of Common Osmolytes on Electrostatic and Hydrophobic Surface Forces

    Maharjan, Nischal (2022-11) [Thesis]
    Advisor: Mishra, Himanshu
    Committee members: Nunes, Suzana Pereira; Fatayer, Shadi P.
    Surface forces due to electrostatics and hydrophobic interactions in aquatic media are implicated in numerous phenomena in natural and applied contexts, such as protein folding, ATP synthesis, flocculation, froth flotation, food and beverage industry, and separation and purification processes. Although the effects of hard ions like K+ and Cl- on such surface forces have been extensively studied and well understood, the effects of common osmolytes such as urea, TMAO, betaine, sarcosine, and glycine on electrostatics and the hydrophobic interaction are not entirely clear. In the recent years, direct surface force measurements are being utilized to probe these effects. The expectation is that these findings will bring us one step closer to understanding the balance of surface and molecular forces in extremophiles, e.g., Escherichia coli, Sepia officinalis, and Dasyatis americana. In this thesis, we have utilized Atomic Force Microscopy (AFM) and complimentary techniques to directly quantify the effects of common osmolytes on (i) electrostatic interactions between the charged silica surfaces; and (ii) hydrophobic interactions between perfluorinated surfaces. Urea, TMAO, betaine, sarcosine, and glycine enhanced the magnitude of electrostatic interaction. We provide some clues towards mechanistic insight. For hydrophobic surfaces, urea increased adhesion when perfluorinated surfaces were brought into contact, whereas TMAO, betaine, and sarcosine reduced it in the following order: TMAO > betaine > sarcosine. Advancing/receding contact angles were measured to check whether the osmolytes adsorbed onto the hydrophobic surfaces. Contact angle hysteresis data revealed that the adsorption was not significant, and these findings were corroborated via Quartz Crystal Microbalance with Dissipation experiments. Taken together, our findings advance the current understanding of osmolytes’ effects on electrostatic and hydrophobic interactions.
  • Terrain-Based UAV Positioning: Tractable Models, Generalized Algorithms, and Analytical Results

    Lou, Zhengying (2022-11) [Thesis]
    Advisor: Alouini, Mohamed-Slim
    Committee members: Gao, Xin; Eltawil, Ahmed; Trichili, Abderrahmen
    Deploying unmanned aerial vehicle (UAV) networks to provide coverage for outdoor users has attracted great attention during the last decade. Terrain information requires extensive attention in outdoor UAV networks, and it is one of the most important factors affecting coverage performance. Providing tractable models and common methods is necessary to generalize the terrain-based outdoor UAV positioning strategies. In this thesis, we demonstrate that UAVs can provide stable coverage for regularly moving users based on the existing local terrain reconstruction methods with UAV sampling. Next, a coarse-grained UAV deployment can be performed with a simple set of parameters that characterize the terrain features. A stochastic geometry framework can provide general analytical results for the above coarse-grained UAV networks. In addition, the UAV can avoid building blockage without prior terrain information through real-time linear-trajectory search. We proposed four algorithms related to the combinations of collecting prior terrain information and using real-time search, and then their performances are evaluated and compared in different scenarios. By adjusting the height of the UAV based on terrain information collected before networking, the performance is significantly enhanced compared to the one when no terrain information is available. The algorithm based on real-time search further improves the coverage performance by avoiding the shadow of buildings. During the execution of the real-time search algorithm, the search distance is reduced using the collected terrain information.
  • Cellulose acetate membranes for organic solvent nanofiltration

    Oviedo-Osornio, C. Iluhí (2022-11) [Thesis]
    Advisor: Szekely, Gyorgy
    Committee members: Saikaly, Pascal; Lauersen, Kyle J.
    Organic solvent nanofiltration (OSN) is a membrane-based sustainable alternative to conventional separation techniques because it is non-thermal and energy-efficient. The fabrication of membranes usually includes fossil-based polymers and toxic solvents that present significant challenges. For example, its declining availability, concerns about its degradability and cross-contamination that involve toxicity risks. Nowadays, there is an increasing interest in the development of more sustainable membranes that maintain an optimum performance even in harsh solvents. The aim of my thesis research is to develop stable OSN membranes from cellulose acetate and explore the use of deacetylation reactions. The effect of the degree of acetylation on the membrane performance and stability in different organic solvents was investigated. The chemical composition and morphology were investigated using Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), and Atomic Force Microscopy (AFM). It was found that cellulose acetate membranes with less than 22% acetylation present a satisfactory solvent resistance and rejection in harsh solvents, such as DMF and acetone. In the performance tests were identified two main trends: one for polar protic solvents and one for polar aprotic solvents. This was attributed to their capacity to interact with the membrane via H-bond formation. The molecular weight cutoff (MWCO) was in the range of 735–325 g mol–1 in aprotic solvents and higher than 885 g mol–1 for polar protic solvents. The results found in this research can be translated into a reduce in costs, waste generated, energy required, and time employed in the fabrication of membranes. Also, it opens potential areas in the industry as it can be implemented in harsh solvent environments.
  • Investigation on an underwater solar concentrating photovoltaic-membrane distillation (CPV-MD) integrated system

    Liang, Shen; Zheng, Hongfei; Zhao, Zhiyong; Ma, Xinglong; Ng, Kim Choon (Desalination, Elsevier BV, 2022-10-29) [Article]
    This paper presents an underwater solar concentrating photovoltaic-membrane distillation (CPV-MD) integrated system for regions of coastal cities and islands where land resources are insufficient and suffer from critical shortages in electricity and freshwater. A deformable solar concentrator that works underwater is innovatively designed and matched with the photovoltaic-membrane distillation module. Given its application scenario, the integrated system is designed without metallic components to prevent seawater corrosion. The concentrator's optical characteristics are revealed via optical simulations. The results illustrate that the concentrator bears optimal optical performance when its elastic membrane's deformation ratio α is 0.25 and height ratio γ is 0.35. An experimental setup with a solar cell radius of 50 mm is developed and tested in actual weather to reveal its electricity and freshwater yield performance. It is found that the integrated system exhibits similar performance under the light incident angle of 0°and 10°. Additionally, for the experiment with average solar radiation of 514 W/m2, the integrated system's output power varies between 1.53 W and 1.0 W, with an average electrical efficiency of 3.16 %. The accumulated freshwater yield is 67.8 g, with an average water yield efficiency of 28.5 %. This work may provide a new perspective on underwater solar energy utilization.
  • Plasticization mitigation strategies for gas and liquid filtration membranes - A review

    Chang, Ying Shi; Kumari, Priyanka; Munro, Catherine J.; Szekely, Gyorgy; Vega, Lourdes F.; Nunes, Suzana Pereira; Dumée, Ludovic F. (Journal of Membrane Science, Elsevier BV, 2022-10-28) [Article]
    Plasticization is a major source of performance reduction in polymeric membranes, where uptake of specific vapour or liquid compounds affects either the space between macromolecular chains and thus free volume or directly initiates the partial depolymerization of the polymeric materials. During membrane separations, solutes or major feed components may induce plasticization of the bulk membrane materials, detrimentally affecting the long-term performance and stability of these membranes. This plasticization effect, inherent to operating with polymeric materials, may nevertheless be adjourned through the smart and selective design of materials via crosslinking, polymer blending, functionalization, grafting, and incorporation of nanomaterial additives into the polymer matrix. This review aims at critically presenting recent and relevant approaches tackling the plasticization of glassy polymeric membranes, which occurs during both gas separation and organic solvent filtration. Recommendations for future work, addressing aspects related to both materials and process engineering are proposed here.
  • Lipid Droplets Fuel Small Extracellular Vesicle Biogenesis

    Genard, Geraldine; Tirinato, Luca; Pagliari, Francesca; Da Silva, Jessica; Giammona, Alessandro; Alquraish, Fatema H.; Bordas, Marie; Marafioti, Maria Grazia; Di Franco, Simone; Jansen, Jeanette; Garcia-Calderon, Daniel; Hanley, Rachel; Nistico, Clelia; Fukasawa, Yoshinori; Mueller, Torsten; Krijgsveld, Jeroen; Todaro, Matilde; Costanzo, Francesco Saverio; Stassi, Giorfio; Nessling, Michelle; Richter, Karsten; Maass, Kendra; Liberale, Carlo; Seco, Joao (Cold Spring Harbor Laboratory, 2022-10-24) [Preprint]
    Despite an increasing gain of knowledge regarding small extracellular vesicle (sEV) composition and functions in cell-cell communication, the mechanism behind their biogenesis remains unclear. Here, we revealed for the first time that the sEV biogenesis and release into the microenvironment are tightly connected with another important organelle: Lipid Droplets (LD). We have observed this correlation using different human cancer cell lines as well as patient-derived colorectal cancer stem cells (CR-CSCs). Our results showed that the use of external stimuli such as radiation, pH, hypoxia, or lipid interfering drugs, known to affect the LD content, had a similar effect in terms of sEV secretion. Additional validations were brought using multiple omics data, at the mRNA and protein levels. Altogether, the possibility to fine-tune sEV biogenesis by targeting LDs, could have a massive impact on the amount, the cargos and the properties of those sEVs, paving the way for new clinical perspectives.
  • Computational fluid dynamics simulations of solar-assisted, spacer-filled direct contact membrane distillation: Seeking performance improvement

    Ansari, Abolfazl; Galogahi, Fariba Malekpour; Millar, Graeme; Helfer, Fernanda; Thiel, David V.; Soukane, Sofiane; Ghaffour, NorEddine (Desalination, Elsevier BV, 2022-10-21) [Article]
    Significant downstream performance reduction and concentration polarisation reduce direct contact membrane distillation (DCMD) efficiency. These challenges are not well researched since they are difficult to implement experimentally and numerically. Hence, this study examined the impact of solar absorbers and different spacer filaments upon DCMD performance. A 2D computational fluid dynamics model that considered simultaneous mass and heat transfer across the membrane and throughout the channels was developed to simulate water flux in DCMD modules under the use of solar absorbers and spacer filaments of various designs. The simulation outcomes were in excellent agreement with experimental results provided by two different studies, with the assisted solar absorber module and the spacer-filled module deviating <5 % and 3 % from the experimental results, respectively. A module equipped with the solar absorber membrane enhanced the DCMD performance better than a module with a solar absorber plate. The results also illustrated that a module with cylindrical detached spacer filaments improved DCMD performance more than a module with rectangular and semicircular attached spacers. Finally, it was shown that a module equipped with an integrated developed spacer and solar absorber membrane significantly enhanced water flux and both concentration and temperature polarisations, specifically when the inlet velocity was increased. Water flux and the temperature polarisation coefficient increased by 220 % in the integrated module, and the concentration polarisation coefficient decreased by 10 %. Moreover, the developed module resulted in a substantial increase in downstream performance.
  • First record of Boulenger's anthias Sacura boulengeri (Heemstra 1973) in the Red Sea

    Peinemann, Viktor N. Nunes; Pombo-Ayora, Lucía; Cochran, Jesse; Marchese, Fabio; Chimienti, Giovanni; Rodrigue, Mattie; Eweida, Ameer A.; Marshall, Paul A.; Benzoni, Francesca; Berumen, Michael L. (Journal of Fish Biology, Wiley, 2022-10-20) [Article]
    In November 2020, we observed several individuals and collected one juvenile of an unidentified anthiadine fish (Serranidae) between depths of 250-307m near vertical walls of rocky reefs in the northern Red Sea. Further morphological and molecular analyses revealed that the collected specimen matches Sacura boulengeri, a species previously reported only from the Gulf of Oman to India.
  • Electrochemical iron production to enhance anaerobic membrane treatment of wastewater

    Hu, Zhetai; Zheng, Min; Hu, Shihu; Hong, Pei-Ying; Zhang, Xueqing; Prodanovic, Veljko; Zhang, Kefeng; Pikaar, Ilje; Ye, Liu; Deletic, Ana; Yuan, Zhiguo (Water research, Elsevier BV, 2022-10-07) [Article]
    Although iron salts such as iron(III) chloride (FeCl3) have widespread application in wastewater treatment, safety concerns limit their use, due to the corrosive nature of concentrated solutions. This study demonstrates that local, electrochemical generation of iron is a viable alternative to the use of iron salts. Three laboratory systems with anaerobic membrane processes were set up to treat real wastewater; two systems used the production of either in-situ or ex-situ electrochemical iron (as Fe2+ and Fe2+(Fe3+)2O4, respectively), while the other system served as a control. These systems were operated for over one year to assess the impact of electrochemically produced iron on system performance. The results showed that dosing of electrochemical iron significantly reduced sulfide concentration in effluent and hydrogen sulfide content in biogas, and mitigated organics-based membrane fouling, all of which are critical issues inherently related to sustainability of anaerobic wastewater treatment. The electrochemical iron strategy can generate multiple benefits for wastewater management including increased removal efficiencies for total and volatile suspended solids, chemical oxygen demand and phosphorus. The rate of methane production also increased with electrochemically produced iron. Economic analysis revealed the viability of electrochemical iron with total cost reduced by one quarter to a third compared with using FeCl3. These benefits indicate that electrochemical iron dosing can greatly enhance the overall operation and performance of anaerobic membrane processes, and this particularly facilitates wastewater management in a decentralized scenario.
  • Rank change and growth within social hierarchies of the orange clownfish, Amphiprion percula

    Fitzgerald, Lucy; Harrison, Hugo B.; Coker, Darren James; Saenz-Agudelo, Pablo; Srinivasan, M.; Majoris, John E.; Boström Einarsson, L.; Pujol, Benoit; Bennett-Smith, Morgan; Thorrold, Simon R.; Planes, S.; Jones, G. P.; Berumen, Michael L. (Marine Biology, Springer Science and Business Media LLC, 2022-10-05) [Article]
    Social hierarchies within groups define the distribution of resources and provide benefits that support the collective group or favor dominant members. The progression of individuals through social hierarchies is a valuable characteristic for quantifying population dynamics. On coral reefs, some clownfish maintain size-based hierarchical communities where individuals queue through social ranks. The cost of waiting in a lower-ranked position is outweighed by the reduced risk of eviction and mortality. The orange clownfish, Amphiprion percula, maintains stable social groups with subordinate individuals queuing to be part of the dominant breeding pair. Strong association with their host anemone, complex social interactions, and relatively low predation rates make them ideal model organisms to assess changes in group dynamics through time in their natural environment. Here, we investigate the rank changes and isometric growth rates of A. percula from 247 naturally occurring social groups in Kimbe Island, Papua New Guinea (5° 12′ 13.54″ S, 150° 22′ 32.69″ E). We used DNA profiling to assign and track individuals over eight years between 2011 and 2019. Over half of the individuals survived alongside two or three members of their original social group, with twelve breeding pairs persisting over the study period. Half of the surviving individuals increased in rank and experienced double the growth rate of those that maintained their rank. Examining rank change in a wild fish population provides new insights into the complex social hierarchies of reef fishes and their role in social evolution.
  • Solvent-Resistant and Thermally Stable Polymeric Membranes for Liquid Separations

    Aristizábal, Sandra L (2022-10) [Dissertation]
    Advisor: Nunes, Suzana Pereira
    Committee members: Hadjichristidis, Nikos; Rosado, Alexandre S.; Lively, Ryan P.
    Membrane technology has great potential to complement traditional energy-intensive molecular separation processes such as distillation, with the advantage of low footprint generation. However, this would only be achieved with the development of better membranes able to operate in challenging conditions, including combinations of organic solvents, high temperatures, extreme pHs, and oxidative environments. This dissertation aims to use high-performance polymeric materials that can withstand temperatures of 120 °C in polar aprotic solvents like N,N-dimethylformamide as separation membranes, using different crosslinking strategies and alternative routes for commercially available material processing. The thesis will be divided into two main approaches. The first approach will start from soluble polyimides as precursors, with designed functionalities that allow post-membrane modifications, such as chemical crosslinking, thermal crosslinking, and thermal rearrangement to enhance the material's chemical resistance. The focus will be on the polyimide synthesis by an alternative one-step room-temperature polyhydroxyalkylation reaction. The chemical and thermal crosslinking take place without involving the imide bond, by incorporating a highly tunable functional group (isatin) in the synthesis of the materials. Propargyl as a pendant group will be used for the thermal crosslinking, and hydroxyl group for the thermal rearrangement. In all cases, the obtained membranes were stable in common organic solvents at 120 °C. The second approach will start from intrinsically solvent-resistant and commercially available poly(aryl ether ketone)s, turned into membranes by a closed-loop modification-regeneration strategy, to address long-term separations in organic solvents at high temperatures. We present for the first time porous poly(aryl ether ketone) flat-sheet and hollow fiber membranes prepared without the use of strong acids or high temperatures. Two methodologies are proposed. The developed strategies shall contribute toward avoiding the regular consumption of new materials and waste generation since the polymer used does not require crosslinking for its stability under organic solvents.
  • A multi-method characterization of Elasmobranch & Cheloniidae communities of the north-eastern Red Sea and Gulf of Aqaba

    Garzon, Francesco; Williams, Collin T.; Cochran, Jesse E M; Tanabe, Lyndsey K.; Abdulla, Ameer; Berumen, Michael L.; Habis, Thamer; Marshall, Paul A; Rodrigue, Mattie; Hawkes, Lucy A (PloS one, Public Library of Science (PLoS), 2022-09-30) [Article]
    The Red Sea is particularly biodiverse, hosting high levels of endemism and numerous populations whose extinction risk is heightened by their relative isolation. Elasmobranchs and sea turtles have likely suffered recent declines in this region, although data on their distribution and biology are severely lacking, especially on the eastern side of the basin in Saudi Arabian waters. Here, we present sightings of elasmobranchs and sea turtles across the north-eastern Red Sea and Gulf of Aqaba collected through a combination of survey methods. Over 455 survey hours, we recorded 407 sightings belonging to 26 elasmobranch species and two sea turtle species, more than 75% of which are of conservation concern. We identified 4 species of rays and 9 species of sharks not previously recorded in Saudi Arabia and report a range extension for the pink whipray (Himantura fai) and the round ribbontail ray (Taeniurops meyeni) into the Gulf of Aqaba. High density of sightings of conservation significance, including green and hawksbill sea turtles and halavi guitarfish were recorded in bay systems along the eastern Gulf of Aqaba and the Saudi Arabian coastline bordering the north-eastern Red Sea, and many carcharhinid species were encountered at offshore seamounts in the region. Our findings provide new insights into the distribution patterns of megafaunal assemblages over smaller spatial scales in the region, and facilitate future research and conservation efforts, amidst ongoing, large-scale coastal developments in the north-eastern Red Sea and Gulf of Aqaba.
  • Biomass generation and heterologous isoprenoid milking from engineered microalgae grown in anaerobic membrane bioreactor effluent

    de Freitas, Barbara Caterina Bastos; Overmans, Sebastian; Medina, Julie Sanchez; Hong, Pei-Ying; Lauersen, Kyle J. (Cold Spring Harbor Laboratory, 2022-09-30) [Preprint]
    Wastewater (WW) treatment in anaerobic membrane bioreactors (AnMBR) is considered more sustainable than in their aerobic counterparts. However, outputs from AnMBR are mixed methane and carbon dioxide gas streams as well as ammonium- (N) and phosphate- (P) containing waters. Using AnMBR outputs as inputs for photoautotrophic algal cultivation can strip the CO2 and remove N and P from effluent which feed algal biomass generation. Recent advances in algal engineering have generated strains for concomitant high-value side product generation in addition to biomass, although only shown in heavily domesticated, lab-adapted strains. Here, investigated whether such a strain of Chlamydomonas reinhardtii could be grown directly in AnMBR effluent with CO2 at concentrations found in its off-gas. The domesticated strain was found to proliferate over bacteria in the non-sterile effluent, consume N and P to levels that meet general discharge or reuse limits, and tolerate cultivation in modelled (extreme) outdoor environmental conditions prevalent along the central Red Sea coast. High-value co-product milking was then demonstrated, up to 837 micro g / L culture in 96 h, in addition to algal biomass production, ~2.4 g CDW / L in 96 h, directly in effluents. This is the first demonstration of a combined bio-process that employs a heavily engineered algal strain to enhance the product generation potentials from AnMBR effluent treatment. This study shows it is possible to convert waste into value through use of engineered algae while also improve wastewater treatment economics through co-product generation.

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