2 Sep 2025

Morphology Control in Waterborne Polyurethane Dispersion Nanocomposites Through Tailored Structure, Formulation, and Processing

Abstract: Waterborne polyurethane dispersions (PUDs) have garnered increasing interest in recent years due to the growing demand for environmentally friendly materials. The unique phase-separated morphologies exhibited in PUD films and coatings provide opportunities for directing the distribution of functional additives and controlling properties. Although there has been extensive research on polyurethanes for several decades, the mechanisms underlying the PUD morphology formation are poorly understood. The morphologies are driven by interactions between hard segments (HS), and the process is further complicated by the presence of colloidal particles and the intricate interaction between the urethane/urea linkages and water. In this work, structure−property-processing relationships between HS content and structure, relative humidity, particle size, and the resulting dry film morphology of PUDs were determined in two diisocyanate systems: hexamethylene diisocyanate (HDI), a symmetric, flexible diisocyanate; and isophorone diisocyanate (IPDI), an asymmetric, sterically hindered cyclic diisocyanate. HDI-based films exhibited semicrystalline morphologies with HS superstructures that are sensitive to relative humidity. IPDI-based films displayed spherical coalescence-suppressed morphologies influenced by particle size and zeta potential. PUD compositions and processing conditions were controlled to produce nanocomposite films with an enhanced dispersion of nanoadditives.

2 Sep 2025

Airborne Bacteria over Thawing Permafrost Landscapes in the Arctic

Abstract: Rapid warming in the Arctic, outpacing global rates, is driving significant changes in cryospheric landscapes, including the release of long-preserved microorganisms. This study focuses on thawing permafrost in Northern Alaska, where microbes previously preserved in frozen soils are introduced into thermokarst lakes, rivers, and coastal waters and may also become airborne as bioaerosols. We present the first microbial composition measurements of bioaerosols in Alaska, identifying their local sources, such as soils, water bodies, and vegetation. Although sea/brackish water is the dominant bioaerosol contributor, we provide the first evidence of permafrost microbial signatures in bioaerosols from permafrost-laden regions. Permafrost is highly enriched with ice nucleating particles (INPs), which play a crucial role in cloud formation, precipitation processes, and radiation budget despite their relatively low atmospheric concentrations. With rising Arctic temperatures, increased permafrost thaw could result in higher levels of airborne permafrost-derived microbes and biological INPs active at warmer subzero temperatures. This, in turn, could enhance precipitation, further accelerating the permafrost thaw. Our findings emphasize the complex interactions between terrestrial changes and atmospheric processes, revealing a potential feedback loop that could intensify permafrost thaw and its broader environmental impacts.

2 Sep 2025

Coastal Hazards System–Gulf of Mexico (CHS-GoM)

Abstract: The US Army Corps of Engineers completed the South Atlantic Coastal Study (SACS) to quantify storm surge and wave hazards, expanding the Coastal Hazards System (CHS) to the South Atlantic Division (SAD) domain. The goal of CHS-SACS was to quantify coastal storm hazards for present conditions and future mean sea level fluctuation scenarios to reduce flooding risk and increase resiliency in coastal environments. CHS-SACS was completed for three regions within the SAD domain, and this report focuses on the Gulf of Mexico (CHS-GoM). This study applied the CHS’ Probabilistic Framework with Joint Probability Method Augmented by Metamodeling Prediction (JPM-AMP) to perform a probabilistic coastal hazard analysis (PCHA) of tropical cyclone (TC) and extratropical cyclone (XC) responses, including new atmospheric and hydrodynamic numerical model simulations of synthetic TCs and historical XCs. This report documents the CHS probabilistic framework for the CHS-GoM region by executing the JPM-AMP, and comprising storm climate characterization, storm sampling, storm recurrence rate estimation, marginal distributions, correlation and dependence structures of TC atmospheric-forcing parameters, development of augmented storm suites, and assignment of discrete storm weights to the synthetic TCs. Coastal hazards were quantified for annual exceedance frequencies over the range of 10 yr−1 to 10−4 yr−1.

29 Aug 2025

Nanofiber Fabrication by Electrospinning Technology: Optimization, Characterization, and Application

Abstract: This project explores electrospinning (ES) as one of the most successful technologies to produce nanofiber materials. Electrospun nanofibers are used in various military technologies, including advanced filtration systems, impact-resistant protective gear, thermal insulation, radar absorption for camouflage and stealth, antimicrobial wound dressings, drug-delivery patches, rapid healing, efficient solar cells, and self-cleaning materials for regeneration. Researchers at the US Army Engineer Research and Development Center (ERDC) investigated electrospinning effects on morphology, crystallinity and distribution of metal oxides for photocatalytic activities, and magnetic and mechanical properties in reinforcing composites. This study includes the following fabricated electrospun mats: -iron and titanium oxide (Fe3O4 and TiO2) with polyvinyl alcohol (PVA) -graphene, graphene oxide, and reduced graphene oxide with polyvinylidene fluoride (PVDF) -graphene-polyacrylonitrile (PAN) -metal-organic frameworks (MOF), graphene-MXene with PAN The research presented herein includes electrospinning theory, process, and parameters; sol–gel technology in solution preparation; and electrospinning sample characterization to guide readers in the fabrication of electrospun fibers with targeted characteristics. Future studies explore electrospun MOFs and MXene, a class of two-dimensional inorganic compounds with transition metal carbides, nitrides, or carbonitrides composites. These studies are invaluable for advancing military programs and enhancing warfighter support and civil works.

29 Aug 2025

Developing Conceptual Ecological Models for Hydraulic Analysis

Purpose: Technological advances, coupled with increased availability of spatial and monitoring data for hydraulic analysis, environmental flows analysis, and remote sensing, present opportunities for novel investigations of the structure and function of ecological systems. To leverage these capabilities in ecological analysis, it is necessary to develop a framework that links engineering model capacities with ecological principles. It is well known that riverine ecosystems are complex systems at the intersection of channel form, stream flow volume, and biology. However, because of differences in technical language and analytical philosophy, there are practical challenges associated with cross-walking multidiscipline riverine studies into interdisciplinary efforts that comprehend both engineering and ecological principles. Challenges associated with cross-discipline communication and framing the scope of ecohydraulic analysis are inherent barriers that limit the traction of research crossing disciplinary boundaries.

29 Aug 2025

Monitoring of Understudied Wetlands: State of Knowledge

Abstract: Some wetlands can present unique challenges for mapping and monitoring due to their size, location, foliage architecture, and spectral characteristics. For instance, assessing ecological condition and restoration success using traditional remote-sensing systems in forested and ephemeral wetlands is onerous. Therefore, the purpose of this technical note is to evaluate the state of knowledge and technology related to the use of remote sensing in assessing vegetation dynamics in understudied and hard to monitor wetlands. Ultimately, this exercise will identify data gaps and recommend improvements for analyzing and modeling wetland systems and trends, quantifying disturbance impacts, and assist efficiencies of data collection to improve management decisions, which in turn will help in reaching restoration goals.

29 Aug 2025

Adaptive Management Framework for Microseira wollei in Lake St. Clair, Michigan

Abstract: Microseira wollei has grown to problematic densities within Lake St. Clair, located between Lake Erie and Lake Huron. Though stakeholders have issued a call-to-action for the management of M. wollei, no substantive plan exists, which was the impetus for this adaptive management framework. Field surveys, emerging technologies, laboratory evaluations, and a literature review were integrated to develop this site-specific frame-work. Adaptive management consists of a series of iterative steps to define and characterize the issue; identify goals, plan, and prioritize; determine a plan; implement management; measure the outcomes; and adapt and re-fine the plan. M. wollei is widely distributed within the study area and across large sections of the lake bed. Due to its large spatial extent, long-term management should focus on regaining and maintaining uses within Lake St. Clair that have been affected by shoreline accumulations. Mechanical removal is anticipated to be the most effective tool; however, the potential addition of algaecides or nutrient sequestration products could be explored for increased effectiveness. The planning and execution of a substantive management plan for M. wollei in Lake St. Clair are outlined and described, but effective management will require a concerted effort on a scale that matches the scope of the problem.

28 Aug 2025

South Atlantic Coastal Study (SACS) Calibration and Validation of the Coastal Storm Modeling System (CSTORM) for Water Levels and Waves Part 3. Gulf of Mexico Domain

Abstract: The US Army Corps of Engineers, South Atlantic Division, is currently engaged in the South Atlantic Coastal Study. One of the phases of this study is focused on conducting coastal storm modeling for the eastern and central Gulf of Mexico coastline of the United States. This technical report details the development of input for the Coastal Storm Modeling System (CSTORM) suite of models (WAVEWATCH III, ADCIRC, and STWAVE) for this project and presents the efforts made to calibrate model setups and validate results for eight historical tropical storm events impacting the study area.

28 Aug 2025

South Atlantic Coastal Study (SACS) Calibration and Validation of the Coastal Storm Modeling System (CSTORM-MS) for Water Levels and Waves: Part 2. South Atlantic Coast Domain

Abstract: The US Army Corps of Engineers, South Atlantic Division, is currently engaged in the South Atlantic Coastal Study. One of the phases of this study is focused on conducting coastal storm modeling for the southern Atlantic coastline of the United States. This technical report details the development of input for the Coastal Storm Modeling System suite of models (WAVEWATCH III, ADCIRC, and STWAVE) for this project and presents the efforts made to calibrate model setups and validate results for seven historical tropical storm events impacting the study area.

28 Aug 2025

South Atlantic Coastal Study (SACS) Calibration and Validation of the Coastal Storm Modeling System (CSTORM-MS) for Water Levels and Waves: Part 1: Puerto Rico / US Virgin Island Domain

Abstract: The US Army Corps of Engineers, South Atlantic Division, is currently engaged in the South Atlantic Coastal Study. One of the phases of this study is focused on conducting coastal storm modeling for the Puerto Rico and US Virgin Islands. This technical report details the development of input for the Coastal Storm Modeling System suite of models (WAVEWATCH III, ADCIRC, and STWAVE) for this project and presents the efforts made to calibrate model setups and validate results for four historical tropical storm events impacting the study area.