19 Mar 2025

Peptide Display for Rare Earth Element Binding

Abstract: Rare earth elements (REEs) are metals that are indispensable to the function of many advanced systems and materials. The supply chain of REEs is heavily dependent on foreign sources and supply shortages are a major concern to the US government. Biological recovery approaches could be an economically feasible approach to recover REEs from unconventional or secondary sources. The objective of this project was to express a lanthanide-binding tag, with an affinity for adsorption of REEs, on the surface of the biomining bacterium, Acidithiobacillus ferrooxidans. This was to be accomplished using synthetic biology tools. The initial cloning steps were performed in Escherichia coli, since techniques are well established in this strain. Using a peptide display approach, several DNA constructs with the binding tag were designed that were regulated by constitutive or inducible promoters and cloned into plasmids that replicate in E. coli and A. ferrooxidans. All plasmids were observed to be unstable or lethal in E. coli, exhibiting sequence rearrangements or deletion of the designed construct. Conjugation between E. coli and A. ferrooxidans and subsequent REE binding assays were thus not possible due to the absence of a structurally and functionally intact plasmid.

13 Mar 2025

Seasonality of Solute Flux and Water Source Chemistry in a Coastal Glacierized Watershed Undergoing Rapid Change: Wolverine Glacier Watershed, Alaska

Abstract: As glaciers rapidly lose mass, the tight coupling between glaciers and downstream ecosystems results in widespread impacts on global hydrologic and biogeochemical cycling. Knowledge of seasonally changing hydrologic processes and solute sources and signatures is limited. We conducted a broad water sampling campaign to understand the present-day partitioning of water sources and associated solutes in Alaska’s Wolverine Glacier watershed. We established a relationship between electrical conductivity and streamflow at the watershed outlet dividing the melt season into four hydroclimatic periods. Across hydroclimatic periods, we observed a shift in nonglacial source waters from snowmelt-dominated overland and shallow subsurface flow paths to deeper groundwater flow paths. We also observed the shift from a low- to high-efficiency subglacial drainage network and the associated flushing of water stored subglacially with higher solute loads. We used calcium from watershed outlet samples to estimate solute fluxes for each hydroclimatic period across two melt seasons. Between 40% and 55% of Ca2+ export occurred during the late season rainy period. Partitioning of the melt season coupled with a characterization of the chemical makeup and magnitude of solute export provides new insight into a rapidly changing watershed and creates a framework to quantify and predict changes to solute fluxes.

12 Mar 2025

Old River Control Low Sill Structure: Monitoring and Performance

Abstract: The Old River Low Sill Structure (ORLSS) is located approximately 25 mi south of Vidalia, LA, and is part of the Old River Control Complex. The structure is founded on steel piles and is a 566-foot-long concrete structure constructed in 1959. The structure resembles a dam with 11, 44-foot-wide gates to prevent migration of the Mississippi River’s current course to a hydraulically shorter course down the Atchafalaya River. A re-analysis was undertaken by the US Army Engineer Research and Development Center to investigate the current level of stability and the potential for adjusting the operating limitations placed on the structure because of damage during the 1973 flood. The investigation was performed by reviewing the design and post-design stability analyses, analyzing performance data, and performing an updated stability analysis. The stability analysis was performed with monitoring data that spanned several decades. Using historic monitoring data in the stability analysis, with a wide range of loading conditions, it was shown that uplift conditions were not as severe as previously considered. Performance data coupled with the stability analysis show that the structural performance supports the current operating conditions.

12 Mar 2025

Reading the Ground: Understanding the Response of Bioelectric Microbes to Anthropogenic Compounds in Soil Based Terrestrial Microbial Fuel Cells

Abstract: Electrogenic bacteria produce power in soil based terrestrial microbial fuel cells (tMFCs) by growing on electrodes and transferring electrons released from the breakdown of substrates. The direction and magnitude of voltage production is hypothesized to be dependent on the available substrates. A sensor technology was developed for compounds indicative of anthropological activity by exposing tMFCs to gasoline, petroleum, 2,4-dinitrotoluene, fertilizer, and urea. A machine learning classifier was trained to identify compounds based on the voltage patterns. After 5 to 10 days, the mean voltage stabilized (+/- 0.5 mV). After the entire incubation, voltage ranged from -59.1 mV to 631.8 mV, with the tMFCs containing urea and gasoline producing the highest (624 mV) and lowest (-9 mV) average voltage, respectively. The machine learning algorithm effectively discerned between gasoline, urea, and fertilizer with greater than 94% accuracy, demonstrating that this technology could be successfully operated as an environmental sensor for change detection.

12 Mar 2025

Collaborative Development of Natural and Nature-Based Solutions for Coastal Resiliency in the Arctic and Adjacent Regions: A Workshop

The workshop “Collaborative Development of Natural and Nature-Based Solutions for Coastal Resiliency in the Arctic and Adjacent Regions” was held in Reston, Virginia, October 24–25, 2023. The objective was to assemble diverse international partners in a hybrid in-person and virtual setting to focus on the viability of applying Nature-Based Solutions (NBS) to solve engineering challenges in the Arctic and similar cold region locations. The goals of the two-day workshop were to share recent efforts implementing NBS to mitigate coastal hazards such as flooding and erosion in northern high latitude settings and identify requirements and develop a robust program of activities to advance this work at national, regional, and local levels. This workshop report documents the presentations and discussion and summarizes key needs and recommendations for future engagement identified by speakers and workshop participants.

7 Mar 2025

Coupling Electrokinetics and Phytoremediation to Remove Uranium from Contaminated Soil: A Laboratory Pilot-Scale Study

Abstract: Uranium is a naturally occurring trace element and radionuclide. Uranium is introduced to the environment anthropogenically because of industrial, military, and nuclear energy activities. The approach of coupled electrokinetic phytoremediation has been used to remove other heavy metals from contaminated soil. The objectives here are to investigate the distribution and solubility of uranium in soils with UO2, UO, and uranyl, and examine the processes of coupled electrokinetic phytoremediation in removing U from soils with perennial ryegrass at a laboratory pilot scale. A low-intensity direct electric current field was applied to the contaminated soil for 7 d at 8 h·d−1 after ryegrass was grown for 2 weeks, then, polarity reversal was employed for another 7 d at 8 h·d−1. The uranium redistribution took place among various solid-phase components due to changes in the pH and chemistry of the electrolyte solution. The electrokinetic field increased the U bioavailability in soils as water-soluble U and exchangeable U in contaminated soils with all U species. Thus, the EKF significantly increased the U uptake and bioaccumulation by ryegrass. The current laboratory pilot-scale test confirmed our previous observation from the pot greenhouse study–the coupled electrokinetic phytoremediation may have potential for application in remediating U-contaminated sites.

6 Mar 2025

Effect of Fighter Aircraft Traffic on Full-Depth Reclamation with Thin Surface Layers

Abstract: The US Army Engineer Research and Development Center (ERDC) constructed a full-scale test section to evaluate the effectiveness of different pavement surface technologies in sustaining fighter aircraft traffic. A deteriorated thin asphalt pavement was recycled utilizing full-depth reclamation (FDR) techniques with cement stabilization. Relatively thin surfacing solutions constructed with either conventional hot mix asphalt (HMA) or nontraditional surface materials were placed on the FDR layer and trafficked with a single-wheel F-15 load cart. Rutting behavior, instrumentation response, and nondestructive evaluation measurements were monitored during traffic. Experimental results showed that thin surface treatments and microsurfacing materials placed on FDR layers were capable of supporting an extremely limited number of F-15 operations, and the generation of foreign object debris (FOD) was a major concern. A 4 in. thick HMA layer was required to sustain a meaningful number of F-15 operations, that is, approximately 3,000, and a 2 in. thick HMA layer was required to sustain approximately 100 F-15 passes. An analysis using the Airfield Pavement Evaluation subroutine in PCASE suggested that existing stabilized equivalency factors were reasonable when the minimum asphalt layer thickness was specified. A reduced equivalency factor was observed when the asphalt layer thickness was less than the minimum thickness.

6 Mar 2025

New Construction Criteria for a Changing Arctic and Subarctic: The UFC 3-130 Series Revision Process

Abstract: The DoD operates significant and strategically important installations in the Arctic and Subarctic domain. Geopolitical, economic, and climatic changes require an upgraded ability to rapidly deploy and sustain forces into Arctic and Subarctic regions. Relevant engineering criteria and guidance to support these efforts are the Unified Facility Criteria 3-130–Arctic and Subarctic Construction (UFC 3-130) documents, originally a seven-volume series. The series has been ‘inactive’, indicating the specifications are not current and potentially technically noncompliant. Therefore, designers may resort to methods that do not meet current military or civilian standards, or they may use the outdated guidance leading to costly design and construction failures. Infrastructure owners and operators must be confident that up-to-date technology and criteria are specified to ensure life safety, mission readiness, and infrastructure longevity. This report highlights the process and resources used to generate a new five-volume UFC Arctic and Subarctic series that aligns with current technology and standards while also addressing a changing climate. These new documents are appliable for use by planners, engineers, and architects when planning, designing, constructing, and maintaining DoD infrastructure. The full UFC 3-130 series is available on the Whole Building Design Guide (WBDG) website at https://www.wbdg.org/dod/ufc.

6 Mar 2025

Norfolk Harbor Navigation Improvements Project: Modeling of Dredged Material Placement Schemes and Long-Term Sediment Transport at the Dam Neck Ocean Disposal Site

Abstract: US Army Corps of Engineers–Norfolk District requested assistance with the development and evaluation of dredged-material-placement schemes that evenly distribute placed material and avoid or minimize unacceptable mounding in accordance with the site management and monitoring plan. A multiple placement fate and transport modeling study was conducted to determine the optimal placement plan for dredged material from Thimble Shoals Channel and Atlantic Ocean Channel at the Dam Neck Ocean Disposal Site (DNODS). Provided the large volume of dredged material to be placed at DNODS over a short duration during the construction period, a modeling study was performed using the Geophysical Scale Multi-Block (GSMB) modeling system to determine the transport and fate of placed dredged material at the DNODS that is resuspended by currents and waves over a 2-year period. Six scenarios were undertaken to determine the best path forward. Scenarios 1 and 4 were excluded due to high exceedance of the depth threshold. Scenarios 2, 3, 5, and 6 yielded an approximate 1%–2% dispersal of placed materials from the DNODS during ambient environmental conditions; Scenario 6 yielded the least. Most dispersion occurred during two simulated hurricanes. The model findings generally support the DNODS Environmental Impact Statement and site-designation documents.

3 Mar 2025

Low-Sill Control Structure: Physical Modeling Investigation—Potential Upstream Dike Fields

Abstract: The model investigation reported herein describes the process to analyze the effects of proposed dikes in various locations upstream of the Low-Sill Control Structure (LSCS) using an existing 1:55 Froude-scaled physical model. The purpose of this effort was to utilize the physical model to explore potential configurations of river-training structures in the approach channel that would result in more uniform flow conditions at the structure. This analysis was conducted by constructing dikes out of both sandbags and rock. Each dike configuration was surveyed using lidar and then tested by collecting particle-tracking velocimetry data. A total of nine dike configurations were tested in the physical model, and the resulting flow fields in the approach channel were provided to the US Army Corps of Engineers, Mississippi Valley Division. Most configurations resulted in data that showed improved, straighter flow paths in the approach channel. The results of these tests indicated that an L-head dike configured as the 50 ft stone dike 1-23A provided relatively straight flow conditions approaching the LSCS with relative uniform velocities across the channel.