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Open access publications by faculty, postdocs, and graduate students in the Department of Civil and Environmental Engineering.
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Item The Influence of Seasonal Effects on Railway Vertical Track Modulus(Infrastructures, 2024-07-23) Merheb, Antonio; Palese, Joseph; Hartsough, Christopher M.; Zarembski, Allan; Bernucci, LiediAdequate vertical track support is essential for safe and efficient railway operations. Insufficient support leads to distorted track geometry, increased dynamic loads, component stress, poor ride quality, rolling stock damage, and derailment risks. Current inspection practices focus on assessing the condition of the track components and geometry, rather than the root causes of degradation. To improve this condition, this study presents the use of a methodology that utilizes an autonomous vertical track deflection measurement system mounted on a loaded rail car (36 tonnes/axle) to support track maintenance decisions in a heavy haul railroad located in southeast Brazil. The system continuously measured substructure stiffness along the railway line. Over one year, data were collected from over 8000 km of track. The study highlighted seasonal effects on track degradation over time, identifying areas with significant deflections and high deflection rates, which contribute to issues such as differential settlement and reduced lifespan of track components. Additionally, the study revealed seasonal effects, with deflections peaking during wet weather and decreasing during dry cycles. A method to classify weak track areas was developed, facilitating monitoring and enabling more effective maintenance planning, contributing to the reduction of overall track maintenance costs and enhancing safety and operational efficiency.Item Distribution and composition of redox-active species and dissolved organic carbon in Arctic lacustrine porewaters(Arctic, Antarctic, and Alpine Research, 2024-07-22) Xin, Danhui; Hudson, Jeffrey M.; Sigman-Lowerya, Anthony; Chin, Yu-PingThe interaction between redox-active species and dissolved organic carbon (DOC) is crucial in driving lacustrine benthic microbial processes. In lacustrine porewaters, many redox-active species exist in their reduced form, while DOC acts as a substrate and an electron acceptor. Understanding the types and abundance of redox-active species in porewaters along with their complementary DOC substrate is pivotal for gaining insights into benthic processes, particularly in regions susceptible to climate change. We report the in-situ measurement of redox-active species in sediment porewaters, alongside the ex-situ measurement of DOC extracted from cores collected from two Arctic lakes (Toolik and Fog 1). Fe2+ was abundantly detected below 4 cm of the sediment-water interface in all cores and was inversely related to dissolved O2. Additionally, two distinct Fe(III)-complexes were identified. DOC ranged in the order of 10s of mg/L and either remained stable or increased with depth. A comparison between Toolik and Fog 1 lakes revealed a higher accumulation of Fe2+ and DOC in the latter. This study marks the first of its kind to assess spatial distributions of redox-active species and DOC as a function of depth from multiple sites in Arctic lacustrine porewaters.Item Non-Equilibrium Scour Evolution around an Emerged Structure Exposed to a Transient Wave(Journal of Marine Science and Engineering, 2024-06-05) Velioglu Sogut, Deniz; Sogut, Erdinc; Farhadzadeh, Ali; Hsu, Tian-JianThe present study evaluates the performance of two numerical approaches in estimating non-equilibrium scour patterns around a non-slender square structure subjected to a transient wave, by comparing numerical findings with experimental data. This study also investigates the impact of the structure’s positioning on bed evolution, analyzing configurations where the structure is either attached to the sidewall or positioned at the centerline of the wave flume. The first numerical method treats sediment particles as a distinct continuum phase, directly solving the continuity and momentum equations for both sediment and fluid phases. The second method estimates sediment transport using the quadratic law of bottom shear stress, yielding robust predictions of bed evolution through meticulous calibration and validation. The findings reveal that both methods underestimate vortex-induced near-bed vertical velocities. Deposits formed along vortex trajectories are overestimated by the first method, while the second method satisfactorily predicts the bed evolution beneath these paths. Scour holes caused by wave impingement tend to backfill as the flow intensity diminishes. The second method cannot sufficiently capture this backfilling, whereas the first method adequately reflects the phenomenon. Overall, this study highlights significant variations in the predictive capabilities of both methods in regard to the evolution of non-equilibrium scour at low Keulegan–Carpenter numbers.Item A Hyperelastic Bounding Surface Plasticity Model for Unsaturated Granular Soils(Geosciences, 2024-05-30) Kadivar, Mehdi; Manahiloh, Kalehiwot Nega; Kaliakin, Victor N.In this paper, a state-dependent, bounding surface plasticity model that simulates the behavior of unsaturated granular soils is presented. An unsaturated, soil mechanics-compatible elastoplastic response is adopted in which no part of the response occurs in a purely elastic fashion. To create an appropriate hydro-mechanical coupling, a newer generation stress framework, consisting of the Bishop-type effective stress and a second stress variable, is used in conjunction with a soil-water characteristic curve function. Details regarding the model development, parameter estimation, and assessment of the model’s predictive capabilities are outlined. With a single set of parameter values, the model realistically simulates the main features that characterize the shear and volumetric behavior of unsaturated granular soils over a wide range of matric suction, density, and net confining pressure.Item Core–Shell Rubber Nanoparticle-Modified CFRP/Steel Ambient-Cured Adhesive Joints: Curing Kinetics and Mechanical Behavior(Materials, 2024-02-04) Okeola, Abass Abayomi; Hernandez-Limon, Jorge E.; Tatar, JovanExternally bonded wet-layup carbon fiber-reinforced polymer (CFRP) strengthening systems are extensively used in concrete structures but have not found widespread use in deficient steel structures. To address the challenges of the adhesive bonding of wet-layup CFRP to steel substrates, this study investigated the effect of core–shell rubber (CSR) nanoparticles on the curing kinetics, glass transition temperature (𝑇𝑔) and mechanical properties of ambient-cured epoxy/CSR blends. The effects of silane coupling agent and CSR on the adhesive bond properties of CFRP/steel joints were also investigated. The results indicate that CSR nanoparticles have a mild catalytic effect on the curing kinetics of epoxy under ambient conditions. The effect of CSR on the 𝑇𝑔 of epoxy was negligible. Epoxy adhesives modified with 5 to 20%wt. of CSR nanoparticles were characterized with improved ductility over brittle neat epoxy; however, the addition of CSR nanoparticles reduced tensile strength and modulus of the adhesives. An up to 250% increase in the single-lap shear strength of CFRP/steel joints was accomplished in CSR-modified joints over neat epoxy adhesive joints.Item A Bacillus velezensis strain shows antimicrobial activity against soilborne and foliar fungi and oomycetes(Frontiers in Fungal Biology, 2024-02-23) Wockenfuss, Anna; Chan, Kevin; Cooper, Jessica G.; Chaya, Timothy; Mauriello, Megan A.; Yannarell, Sarah M.; Maresca, Julia A.; Donofrio, Nicole M.Biological control uses naturally occurring antagonists such as bacteria or fungi for environmentally friendly control of plant pathogens. Bacillus spp. have been used for biocontrol of numerous plant and insect pests and are well-known to synthesize a variety of bioactive secondary metabolites. We hypothesized that bacteria isolated from agricultural soil would be effective antagonists of soilborne fungal pathogens. Here, we show that the Delaware soil isolate Bacillus velezensis strain S4 has in vitro activity against soilborne and foliar plant pathogenic fungi, including two with a large host range, and one oomycete. Further, this strain shows putative protease and cellulase activity, consistent with our prior finding that the genome of this organism is highly enriched in antifungal and antimicrobial biosynthetic gene clusters. We demonstrate that this bacterium causes changes to the fungal and oomycete hyphae at the inhibition zone, with some of the hyphae forming bubble-like structures and irregular branching. We tested strain S4 against Magnaporthe oryzae spores, which typically form germ tubes and penetration structures called appressoria, on the surface of the leaf. Our results suggest that after 12 hours of incubation with the bacterium, fungal spores form germ tubes, but instead of producing appressoria, they appear to form rounded, bubble-like structures. Future work will investigate whether a single antifungal molecule induces all these effects, or if they are the result of a combination of bacterially produced antimicrobials.Item The Impact of Sea Level Rise on Roadway Design and Evacuation Routes in Delaware(American Journal of Climate Change, 2024-03-29) Palevich, Jack; Faghri, Ardeshir; Karakurt, AhmetAs the global temperature continues to increase, the sea level continues to rise at a rapid rate that has never been seen before. This becomes an issue for many facets of life but one of the most impacted is the transportation infrastructure. Many people living in low elevation coastal areas can become trapped by flooding with no way in or out. With Delaware being a coastal state, this would affect a large portion of the population and will have detrimental effects over time if nothing is done to combat sea level rise. The issue with sea level rise in transportation is that once the roads become flooded, they become virtually unusable and detour routes would be needed. If all the roads in a coastal area were to be affected by sea level rise, the options for detours would become limited. This article looks at direct solutions to combat sea level rise and indirect solutions that would specifically help transportation infrastructure and evacuation routes in Delaware. There is not one solution that can fix every problem, so many solutions are laid out to see what is applicable to each affected area. Some solutions include defense structures that would be put close to the coast, raising the elevation of vulnerable roads throughout the state and including pumping stations to drain the water on the surface of the road. With an understanding of all these solutions around the world, the ultimate conclusion came in the form of a six-step plan that Delaware should take in order to best design against sea level rise in these coastal areas.Item ChemisTree: A Novel, Interactive Chemistry Game to Teach Students about Electron Configuration(Journal of Chemical Education, 2024-01-12) Goldman, Slade; Coscia, Katie A.; Genova, Lauren A.Electron configuration provides insight into the chemical behaviors of elements and is an important concept for students to master in introductory chemistry. To better strengthen undergraduate students’ mastery of electron configurations of atoms and ions, we designed a novel, interactive chemistry game called ChemisTree that uses active-learning techniques (e.g., physically building electron configurations onto a game board, small group work, and whole class discussion) and incorporates the three rules for electrons filling orbitals (Aufbau principle, Pauli exclusion principle, and Hund’s rule), using LEGO tiles and plates to represent electrons and orbitals. Students watch an introductory video explaining the rules and components of the game prior to applying their knowledge of electron configuration by working in small groups to build the orbital diagrams of atoms and ions using the materials provided in their ChemisTree game kits. Student understanding is assessed using multiple-choice pre/post-test questions, scoring sheets with peer discussion, and self-reported postactivity evaluations. Students who played the game scored significantly higher in the post-test (62.7%) compared to the pre-test (51.2%), representing an 11.5% increase in average score. Here we provide details about the activity and present data suggesting that student understanding of electron configuration is improved.Item Urban Ecohydrology: Accounting for Sub-Grid Lateral Water and Energy Transfers in a Land Surface Model(Water Resources Research, 2024-03-25) Alexander, G. Aaron; Voter, Carolyn B.; Wright, Daniel B.; Loheide, Steven P. IIAlthough urbanization fundamentally alters water and energy cycles, contemporary land surface models (LSMs) often do not include key urban vegetation processes that serve to transfer water and energy laterally across heterogeneous urban land types. Urban water/energy transfers occur when rainfall landing on rooftops, sidewalks, and driveways is redirected to lawns or pervious pavement and when transpiration occurs from branches overhanging impervious surfaces with the corresponding root water uptake takes place in nearby portions of yards. We introduce Noah-MP for Heterogenous Urban Environments (Noah-MP HUE), which adds sub-grid water transfers to the widely used Noah-MP LSM. We examine how sub-grid water transfers change surface water and energy balances by systematically increasing the amount of simulated water transfer for four scenarios: tree canopy expanding over pavement (Urban Tree Expansion), tree canopy shifting over pavement (Urban Tree Shift), and directing impermeable runoff onto surrounding vegetation (Downspout Disconnection) or into an engineered pavement (Permeable Pavement). Even small percentages of sub-grid water transfer can reduce runoff and enhance evapotranspiration and deep drainage. Event-scale runoff reduction depends on storm depth, rainfall intensity, and antecedent soil moisture. Sub-grid water transfers also tend to enhance (reduce) latent (sensible) heat. Results highlight the importance not only of fine-scale heterogeneity on larger scale surface processes, but also the importance of urban management practices that enhance lateral water transfers and water storage–so-called green infrastructure–as they change land surface fluxes and, potentially, atmospheric processes. This work opens a pathway to directly integrate those practices in regional climate simulations. Key Points - We develop an urban land surface model representation of impervious to pervious runon and canopy overhanging impervious surfaces - Using idealized land use, we systematically examine the effects of lateral transfers on water and energy budgets over warm seasons - We found large changes in runoff generation, water balances, and energy partitioning when lateral transfers are simulatedItem Adhesion Characterization and Enhancement between Polyimide-Silica Composite and Nodulated Copper for Applications in Next-Generation Microelectronics(ACS Applied Materials & Interfaces, 2024-01-17) Doshi, Sagar M.; Barry, Alexander; Schneider, Alexander; Parambil, Nithin; Mulzer, Catherine; Yahyazadehfar, Mobin; Samadi-Dooki, Aref; Foltz, Benjamin; Warrington, Keith; Wessel, Richard; Zhang, Lei; Simone, Christopher; Blackman, Gregory S.; Lamontia, Mark A.; Gillespie, John W. Jr.As the need for high-speed electronics continues to rise rapidly, printed wiring board (PWB) requirements become ever-more demanding. A typical PWB is fabricated by bonding dielectric films such as polyimide to electrically conductive copper foil such as rolled annealed (RA) copper and is expected to become thinner, flexible, durable, and compatible with high-frequency 5G performance. Polyimide films inherently feature a higher coefficient of thermal expansion (CTE) than copper foils; this mismatch causes residual thermal stresses. To attenuate the mismatch, silica nanoparticles may be used to reduce the CTE of PI. A nodulated copper surface can be used to enhance the Cu/PI adhesion by additional bonding mechanisms that could include a type of mechanical bonding, which is a focus of this study. In this investigation, a 90° peel test was used to measure the peel strength in copper/polyimide/copper laminates containing nodulated copper and polyimide reinforced with 0, 20, and 40 wt % silica nanoparticles. The influence of silica nanoparticles on the peel strength was quantitatively evaluated. Laminates incorporating polyimide films lacking silica nanoparticles had a ∼3.75× higher peel strength compared with laminates reinforced with 40% silica. Their failure surfaces were analyzed by using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy to identify the mode of failure and to understand bonding mechanisms. The key bonding mechanism, mechanical interlocking, was achieved when the polyimide surrounded or engulfed the copper nodules when the laminate was created. Post-testing failure surface analysis revealed the presence of copper on the polyimide side and polyimide on the copper side, indicating mixed mode failure. An analytical model was developed to determine the impact of applied pressure, temperature, and time on the polyimide penetration and mechanical interlocking around the copper nodules. The model was validated by measuring the peel strength on another set of specimens fabricated using increased temperature and pressure that showed a 3× increase in peel strength compared to lower temperature/pressure processing conditions. This enhanced adhesion resulted from the lower polymer material viscosity at higher temperatures, which fosters deeper and more complete penetration around the copper nodules during processing at higher pressures for longer durations. The methodology of combining peel testing, viscosity and CTE measurement, SEM/EDX, surface chemical analysis, and penetration depth calculation developed herein enables the calculation of the desired processing parameters to enhance functionality and improve adhesion.Item Predicting road flooding risk with crowdsourced reports and fine-grained traffic data(Computational Urban Science, 2023-03-21) Yuan, Faxi; Lee, Cheng-Chun; Mobley, William; Farahmand, Hamed; Xu, Yuanchang; Blessing, Russell; Dong, Shangjia; Mostafavi, Ali; Brody, Samuel D.The objective of this study is to predict road flooding risks based on topographic, hydrologic, and temporal precipitation features using machine learning models. Existing road inundation studies either lack empirical data for model validations or focus mainly on road inundation exposure assessment based on flood maps. This study addresses this limitation by using crowdsourced and fine-grained traffic data as an indicator of road inundation, and topographic, hydrologic, and temporal precipitation features as predictor variables. Two tree-based machine learning models (random forest and AdaBoost) were then tested and trained for predicting road inundations in the contexts of 2017 Hurricane Harvey and 2019 Tropical Storm Imelda in Harris County, Texas. The findings from Hurricane Harvey indicate that precipitation is the most important feature for predicting road inundation susceptibility, and that topographic features are more critical than hydrologic features for predicting road inundations in both storm cases. The random forest and AdaBoost models had relatively high AUC scores (0.860 and 0.810 for Harvey respectively and 0.790 and 0.720 for Imelda respectively) with the random forest model performing better in both cases. The random forest model showed stable performance for Harvey, while varying significantly for Imelda. This study advances the emerging field of smart flood resilience in terms of predictive flood risk mapping at the road level. In particular, such models could help impacted communities and emergency management agencies develop better preparedness and response strategies with improved situational awareness of road inundation likelihood as an extreme weather event unfolds.Item Diagnostic load testing and assessment of a corroded corrugated metal pipe culvert before rehabilitation(Structure and Infrastructure Engineering, 2023-11-15) Safari, Sajjad; DuBose, Tyler; Head, Monique H.; Shenton, Harry W. III; Tatar, Jovan; Chajes, Michael J.; Karam, Jonathan; Hastings, Jason N.Buried culverts are important structures within the civil infrastructure that convey water beneath roadways, bridges, and other systems while also being load bearing. However, many culverts are deteriorating and reaching the end of their design life span, where assessment methods to determine whether replacement or rehabilitation techniques such as spray applied pipe liners (SAPLs) are needed to extend their service life. In this study, mounted sensors and vision-based measurement techniques are used to assess the in situ conditions of a culvert consisting of corrugated metal pipes before being rehabilitated with geopolymer (cementitious-based) SAPLs. Results from diagnostic load tests (variating from static to dynamic) are presented to evaluate maximum deformations, verify the load-carrying effectiveness of the SAPLs, and compare results to design calculations due to the presence of a live load acting on the culvert.Item pKa prediction of per- and polyfluoroalkyl acids in water using in silico gas phase stretching vibrational frequencies and infrared intensities(Physical Chemistry Chemical Physics, 2023-09-01) Murillo-Gelvez, Jimmy; Dmitrenko, Olga; Torralba-Sanchez, Tifany L.; Tratnyek, Paul G.; Di Toro, Dominic M.To successfully understand and model the environmental fate of per- and polyfluoroalkyl substances (PFAS), it is necessary to know key physicochemical properties (PChPs) such as pKa; however, measured PChPs of PFAS are scarce and of uncertain reliability. In this study, quantitative structure–activity relationships (QSARs) were developed by correlating calculated (M062-X/aug-cc-pVDZ) vibrational frequencies (VF) and corresponding infrared intensities (IRInt) to the pKa of carboxylic acids, sulfonic acids, phosphonic acids, sulfonamides, betaines, and alcohols. Antisymmetric stretching VF of the anionic species were used for all subclasses except for alcohols where the OH stretching VF performed better. The individual QSARs predicted the pKa for each subclass mostly within 0.5 pKa units from the experimental values. The inclusion of IRInt as a pKa predictor for carboxylic acids improved the results by decreasing the root-mean-square error from 0.35 to 0.25 (n > 100). Application of the developed QSARs to estimate the pKa of PFAS within each subclass revealed that the length of the perfluoroalkyl chain has minimal effect on the pKa, consistent with other models but in stark contrast with the limited experimental data available.Item Annulus Void Fill Material for Rehabilitated Sliplined Culverts(The University of Akron, 2023-03) Patnaik, Anil; Alzlfawi, Abdullah; Das, ShagataSliplining is a method used by transportation agencies to rehabilitate deteriorated culverts. In recent years, ODOT discovered a number of sliplined culverts that did not have their annulus void spaces completely filled. Such culverts experience distortion and settlement as well as reduced structural capacity. Field inspections of several sliplined culverts in Ohio in this study confirmed that the lack of complete annulus void filling is a prevalent problem. Filler grout properties, particularly poor flow characteristics, would prevent the grout from completely filling annulus voids. This led to the investigation of grout properties that are most important to achieve good flow and fillability. New mixture proportions of a controlled low-strength material (CLSM) and cellular grout C40 were developed based on extensive laboratory testing. These improved grouts were also mixed in a batching plant at a larger scale and were pumped over a 200-ft length at an upslope of 2.5% to determine the suitability of these grouts in practical applications. Grouting of the annulus voids of 20-foot-long sections was verified using a 36-inch liner pipe sliplined within a 48-inch host pipe. A suggested basis for changes to the relevant ODOT specifications in SS 837 is recommended.Item The Role of Biochar in Regulating the Carbon, Phosphorus, and Nitrogen Cycles Exemplified by Soil Systems(Sustainability, 2021-05-18) Pan, Shu-Yuan; Dong, Cheng-Di; Su, Jenn-Fang; Wang, Po-Yen; Chen, Chiu-Wen; Chang, Jo-Shu; Kim, Hyunook; Huang, Chin-Pao; Hung, Chang-MaoBiochar is a carbon-rich material prepared from the pyrolysis of biomass under various conditions. Recently, biochar drew great attention due to its promising potential in climate change mitigation, soil amendment, and environmental control. Obviously, biochar can be a beneficial soil amendment in several ways including preventing nutrients loss due to leaching, increasing N and P mineralization, and enabling the microbial mediation of N2O and CO2 emissions. However, there are also conflicting reports on biochar effects, such as water logging and weathering induced change of surface properties that ultimately affects microbial growth and soil fertility. Despite the voluminous reports on soil and biochar properties, few studies have systematically addressed the effects of biochar on the sequestration of carbon, nitrogen, and phosphorus in soils. Information on microbially-mediated transformation of carbon (C), nitrogen (N), and phosphorus (P) species in the soil environment remains relatively uncertain. A systematic documentation of how biochar influences the fate and transport of carbon, phosphorus, and nitrogen in soil is crucial to promoting biochar applications toward environmental sustainability. This report first provides an overview on the adsorption of carbon, phosphorus, and nitrogen species on biochar, particularly in soil systems. Then, the biochar-mediated transformation of organic species, and the transport of carbon, nitrogen, and phosphorus in soil systems are discussed. This review also reports on the weathering process of biochar and implications in the soil environment. Lastly, the current knowledge gaps and priority research directions for the biochar-amended systems in the future are assessed. This review focuses on literatures published in the past decade (2009–2021) on the adsorption, degradation, transport, weathering, and transformation of C, N, and P species in soil systems with respect to biochar applications.Item Combustion operating conditions for municipal Waste-to-Energy facilities in the U.S.(Waste Management, 2021-08-01) Giraud, Robert J.; Taylor, Philip H.; Huang, Chin-paoHighlights • Survey of U.S. municipal waste-to-energy (WTE) facilities identified 188 boilers. • These WTE boilers were stratified into nine categories by combustion technology. • WTE boilers typically operate at a gas residence time > 2.4 s above 1160°C. Abstract This paper reports the first known comprehensive survey of combustion operating conditions across the wide range of municipal waste-to-energy facilities in the U.S. The survey was conducted in a step-wise fashion. Once the population of 188 units operating at over 70 facilities was defined, this population was stratified by distinguishing characteristics of combustion technology. Stratum-level estimates for operating conditions were determined from data collected in the survey. These stratum-level values were weighted by corresponding design capacity share and combined to infer national-level operating parameter estimates representative of the overall population. Survey results show that typical municipal waste-to-energy combustion operating conditions in the U.S. are (1) furnace temperature above 1160 °C, (2) gas residence time above 2.4 s, (3) exit gas concentrations of nearly 10% for oxygen (dry basis), and (4) over 16% for moisture. These operating parameter values can serve as benchmarks for laboratory-scale studies representative of municipal waste-to-energy combustion as typically practiced in the U.S. Graphical abstract Available at: https://doi.org/10.1016/j.wasman.2021.07.015Item Biochar and zero-valent iron sand filtration simultaneously removes contaminants of emerging concern and Escherichia coli from wastewater effluent(Biochar, 2023-07-19) Zhu, Linyan; Chattopadhyay, Suhana; Akanbi, Oluwasegun Elijah; Lobo, Steven; Panthi, Suraj; Malayil, Leena; Craddock, Hillary A.; Allard, Sarah M.; Sharma, Manan; Kniel, Kalmia E.; Mongodin, Emmanuel F.; Chiu, Pei C.; Sapkota, Amir; Sapkota, Amy R.Advanced treated municipal wastewater is an important alternative water source for agricultural irrigation. However, the possible persistence of chemical and microbiological contaminants in these waters raise potential safety concerns with regard to reusing treated wastewater for food crop irrigation. Two low-cost and environmentally-friendly filter media, biochar (BC) and zero-valent iron (ZVI), have attracted great interest in terms of treating reused water. Here, we evaluated the efficacy of BC-, nanosilver-amended biochar- (Ag-BC) and ZVI-sand filters, in reducing contaminants of emerging concern (CECs), Escherichia coli (E. coli) and total bacterial diversity from wastewater effluent. Six experiments were conducted with control quartz sand and sand columns containing BC, Ag-BC, ZVI, BC with ZVI, or Ag-BC with ZVI. After filtration, Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated more than 90% (> 1 log) removal of E. coli from wastewater samples, while BC, Ag-BC, BC with ZVI and Ag-BC with ZVI also demonstrated efficient removal of tested CECs. Lower bacterial diversity was also observed after filtration; however, differences were marginally significant. In addition, significantly (p < 0.05) higher bacterial diversity was observed in wastewater samples collected during warmer versus colder months. Leaching of silver ions occurred from Ag-BC columns; however, this was prevented through the addition of ZVI. In conclusion, our data suggest that the BC with ZVI and Ag-BC with ZVI sand filters, which demonstrated more than 99% removal of both CECs and E. coli without silver ion release, may be effective, low-cost options for decentralized treatment of reused wastewater. Graphical Abstract available at: https://doi.org/10.1007/s42773-023-00240-y Highlights - The efficacy of BC, Ag-BC, and ZVI sand filtration, and their combinations, in removing contaminants from reused water was evaluated. - Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated > 90% removal of E. coli. - BC, Ag-BC, BC with ZVI and Ag-BC with ZVI demonstrated efficient removal of selected contaminants of emerging concern.Item Selection of vortex ripple dimensions in sinusoidal oscillatory flows. Part 1. Ripple dimensions and fluid kinematics(Journal of Fluid Mechanics, 2023-04-10) Yue, Liangyi; Hsu, Tian-Jian; Horner-Devine, Alexander R.Subaqueous vortex ripples in equilibrium are characterized by their unique geometry and dimensions. Motivated by the recent direct numerical simulation study of oscillatory turbulent flow over a wavy bottom by Önder & Yuan (J. Fluid Mech., vol. 858, 2019, pp. 264–314), the objective of this study is to further investigate the fluid dynamical controls that determine the distinctive equilibrium dimensions of vortex ripples. We use direct numerical simulations to investigate the differences in flow kinetics between sinusoidal oscillatory flow over equilibrium and out-of-equilibrium vortex ripples. In comparison with the equilibrium case, the spanwise coherent vortices, the averaged bottom shear stress on overlying flow and the shear stress distribution on the ripple surface are identified as the key fluid dynamical controls on equilibrium dimensions. Based on these controls, we propose mechanisms in the selection of vortex ripple dimensions. We observe that the flow adjusts in such a way that the interaction between overlying flow and vortex ripples tends to generate the strongest coherent vortices while the ripple surface (or overlying flow) experiences the smallest shear stress averaged over ripple wavelength during the selection process. Through a triple decomposition of the flow, the component of the ripple-induced fluctuation is found to dictate these fluid dynamical controls, which implies that this component plays an important role in the evolution of vortex ripples.Item Development of a Recyclable Flax Fiber Reinforced Polymer Composite(Composites in Civil Engineering, 2023-06-28) Das, Shagata; Doshi, Sagar; Millan, Emmanuel; Mendez, Damaris; Luckenbill, Dan; Tatar, JovanThis study compared the mechanical properties of a recyclable flax fiber reinforced polymer composite (FFRP) with a covalent adaptable network (CAN) matrix to an FFRP composite with a conventional (unrecyclable) epoxy resin matrix. The results indicated that composites fabricated via vacuum-assisted resin transfer molding (VARTM) exhibited up to 19% higher tensile modulus and strength compared to those fabricated via hand layup, attributed to reduced air void content and more uniform fiber alignment. Microscopy evidence supported by mechanical property tests revealed superior adhesion of the CAN matrix to flax fibers compared to conventional epoxy resin. Additionally, a solvent-based method was demonstrated for separating fibers from the CAN matrix, facilitating reuse or upcycling.Item Modeling the Partitioning of Anionic Carboxylic and Perfluoroalkyl Carboxylic and Sulfonic Acids to Octanol and Membrane Lipid(Environmental Toxicology and Chemistry, 2023-07-13) Torralba-Sanchez, Tifany L.; Di Toro, Dominic M.; Dmitrenko, Olga; Murillo-Gelvez, Jimmy; Tratnyek, Paul G.Perfluoroalkyl carboxylic and sulfonic acids (PFCAs and PFSAs, respectively) have low acid dissociation constant values and are, therefore, deprotonated under most experimental and environmental conditions. Hence, the anionic species dominate their partitioning between water and organic phases, including octanol and phospholipid bilayers which are often used as model systems for environmental and biological matrices. However, data for solvent–water (SW) and membrane–water partition coefficients of the anion species are only available for a few per- and polyfluoroalkyl substances (PFAS). In the present study, an equation is derived using a Born-Haber cycle that relates the partition coefficients of the anions to those of the corresponding neutral species. It is shown via a thermodynamic analysis that for carboxylic acids (CAs), PFCAs, and PFSAs, the log of the solvent–water partition coefficient of the anion, log KSW(A−), is linearly related to the log of the solvent–water partition coefficient of the neutral acid, log KSW(HA), with a unity slope and a solvent-dependent but solute-independent intercept within a PFAS (or CA) family. This finding provides a method for estimating the partition coefficients of PFCAs and PFSAs anions using the partition coefficients of the neutral species, which can be reliably predicted using quantum chemical methods. In addition, we have found that the neutral octanol–water partition coefficient, log KOW, is linearly correlated to the neutral membrane–water partition coefficient, log KMW; therefore, log KOW, being a much easier property to estimate and/or measure, can be used to predict the neutral log KMW. Application of this approach to KOW and KMW for PFCAs and PFSAs demonstrates the utility of this methodology for evaluating reported experimental data and extending anion property data for chain lengths that are unavailable. Environ Toxicol Chem 2023;00:1–12. © 2023 SETAC