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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

WIPP Safety Significant Confinement Ventilation System (SSCVS) Quality Assurance Program - 20237

Construction and major equipment fabrication are underway for a new ventilation exhaust system at the Waste Isolation Pilot Plant (WIPP). The new system will provide continuous HEPA filtration of the exhaust from the WIPP underground while meeting the ventilation demands for expanded waste emplacement and mining operations over the next 40 years. The SSCVS project has proceeded with the awarding of CD-3A for Long Lead Procurements followed by CD-2/3 approval for the construction of the facilities. The SSCVS project team made the decision to increase the quality oversight throughout the complete project per the Project Quality Assurance Plan (PQAP) such that it can ensure the final products meet applicable NQA-1 requirements and general quality requirements, and that the project will proceed to operations without significant delays due to post installation quality concerns. The PQAP was established prior to approval of the project at the CD-2/3 milestone. The SSCVS project has 2 major long lead procurements which commenced with the awarding of CD-3A. These procurements include the HEPA filter housing assemblies and the Exhaust Fans. There are 22 HEPA filter assemblies for the SSCVS, which are designated Safety Significant for pressure boundary confinement, per the approved PDSA. The exhaust fans also have Safety Significant components to maintain the pressure confinement boundary. NWP made the decision to install resident Quality Inspectors at the fabrication facilities to ensure the documentation for each fabricated unit meets all the QA requirements as defined in the respective contract documents. For the construction of the SSCVS Salt Reduction Building (SRB) and New Filter Building (NFB), dedicated, on-site quality inspectors have been utilized to ensure that all work being performed will comply with quality requirements and the Special Inspections as defined in IBC-2015. At each stage of inspection, hold points are placed into the work packages to ensure NWP QA personnel are present to inspect and verify the installations are in accordance with the design specifications, codes and standards. With this level of oversight, NWP anticipates that the level of quality related issues, as seen on multiple other DOE complex site projects, will be avoided and that the commissioning, start-up and hot operations will progress in a timely fashion, as all documentation will be in place and approved prior to initiation of these activities. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Pump-and-Treat Impacts on Aquifer Conditions and the Development of System-Wide Performance Strategies - 20377

The pump-and-treat (P and T) system on the Hanford Site's Central Plateau currently treats multiple contaminants within the 200-ZP-1 operable unit, including nitrate through its biological treatment processes. Although it was initially designed to support the 200-ZP-1 Remedial Action Objectives, the P and T system has evolved in use to address contaminants from other regions of the aquifer as well. The P and T influents are biogeochemically distinct, treating groundwaters with elevated concentrations of cyanide, uranium, technetium-99, and nitrate. Given the varying geochemical signatures from current and potential future sources, operational conditions, and amendments considered for treatment processes, there is a need to identify the impacts that the P and T effluent has on the aquifer, and how the aquifer affects P and T performance. To this end, laboratory efforts have focused on characterizing P and T effluent and its biogeochemical effects on the sediments through a series repacked column experiments. The P and T effluent is rich in particulate matter. A systematic inspection of this particulate matter in the P and T effluent showed significant levels of manganese/iron oxides, calcite crystals, relatively large organic matter molecules, and biomass. Therefore, the column experiments were designed and conducted for four different treatment systems: artificial groundwater, filtered P and T effluent, non-filtered P and T effluent, and chlorinated P and T effluent. Different levels of microbiologically- and geochemically-induced changes in the columns occurred and modified the flow systems. For example, physical filtration occurred in the sediments where the particulate material had accumulated in the top portion of the column. Reactive transport modeling of the laboratory experiments is being carried out so that the reaction network can be extrapolated to the field scale. These simulations will provide predictive evaluations of system performance based on P and T operational changes and aquifer mass loading and capacity estimates. This information can be used to address combined subsurface and operational challenges, such as the need for frequent well redevelopment to maintain injection capacity. This information also provides the technical basis for decisions related to the P and T system operations that support remedy optimization efforts and short- and long-term remedy decisions related to multiple operable units on the Hanford Site Central Plateau. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Innovations in Sustainable Passive Wastewater Treatment - 20236

Sustainable water treatment systems, engineered to mimic natural processes and utilize natural materials, yield economic and environmental benefits through reductions in long term operational inputs, including: power, chemicals, and labor. Golder is an industry leader in the development and implementation of sustainable technologies at operating and closed mines. We continue to innovate these technologies and customize solutions to meet client needs by applying past experience and focused research. Sustainable (or passive) water treatment systems include ponds, wetlands, flow-through natural media beds, and limestone drains. These systems can blend in with a natural environment, are highly cost-effective for long-term water treatment, and can outcompete traditional active treatment technologies. Application of sustainable technologies relative to active technologies can be influenced by the influent water matrix, effluent limitations, flow rate of water requiring treatment, and available land area. In this presentation, four Golder-developed systems are reviewed as case studies, demonstrating our continued progressive approach to advancing sustainable water treatment technologies to meet industry needs. These case studies focus on design innovations and operational performance from data collected from the operational systems. Resources (power, chemicals, labor) required for the operation of each case study are compared with those that would be required for operation of their active treatment technology alternatives. - Case Study 1 presents an anaerobic biochemical reactor (BCR), a technology typically implemented for metals treatment and acid neutralization, for the treatment of sulfate to low concentrations (<250 mg/L). Active treatment via reverse osmosis (RO) membrane filtration is typically required for treatment of sulfate to similar concentrations, this innovation provides potential for sustainable treatment to replace the need for energy, chemical, labor, and waste (brine) intensive RO treatment for specific applications. Magnetite waste rock materials from the site were upcycled for use in this system to provide sequestration of the sulfide generated in the BCR. - Case Study 2 examines another novel application of the conventional BCR, modified for the removal of radionuclides and metals (uranium, radium, and selenium) at a closed uranium mine. - Case Study 3 presents implementation of sustainable treatment for mine drain water from a historic mine site, now a state park with around 100,000 visitors per year. The system includes a pond, wetland, and manganese removal bed surrounded by public trails designed to maintain the character of the park. The system treats for arsenic, iron, and manganese at relatively high flows (up to 1,200 gpm), with large seasonal fluctuations in flow and quality. - Case Study 4 is a unique project for which Golder is currently designing a sustainable treatment system, with no energy input, to treat nitrate in mine water post-closure at a site near the arctic circle. In this unprecedented application, climate, management of freshet, and space availability presented substantial technical challenges. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

The Nature and State of Groundwater Contamination at the Nevada National Security Site: What Have We Learned from Decades of Groundwater Analysis? - 20337

The regulatory framework for remediating radionuclide contamination from underground nuclear testing at the Nevada National Security Site (NNSS) is based on a combination of characterization and modeling studies, monitoring, and institutional controls [1]. Currently, tritium is the largest contributor (∼90%) to the estimated 44.6 million-curie radionuclide inventory resulting from underground testing [2]. Because of its short half-life (12.32 years), its relative contribution reduces below 10% of the total radiologic inventory over the next 120 years as a result of radioactive decay. Although tritium levels are observed well above the Safe Drinking Water Act (SDWA) maximum contaminant levels (MCLs) in groundwater, other radionuclides are well below their MCLs except within the nuclear test near-field (nuclear test cavity and chimney) environment. In fact, most device-derived radionuclides are below their MCL in groundwater even in samples collected from this near-field environment. The distribution of radionuclides following the nuclear detonation greatly influences the availability of potential contaminants for groundwater transport. Tritium is initially distributed in the gas phase, later as tritiated water in steam, and finally as liquid water, and is available to groundwater transport away from the near-field environment. Other radionuclides that are mobile in groundwater are {sup 14}C, {sup 36}Cl, {sup 99}Tc, and {sup 129}I though their radiologic inventory is small when compared to tritium. Many radionuclides (e.g. U, Pu, Am) are incorporated to a significant extent into the melt glass at the bottom of the cavity and are accessible to groundwater primarily through the slow process of glass dissolution. These radionuclides are also adsorbed to the surfaces of the crushed rock within the cavity and chimney which limits their migration in groundwater. Although colloid facilitated transport of radionuclides at the NNSS has been observed [3], radionuclide concentrations decrease with time and migration distances due to desorption and colloid filtration processes. Current studies indicate that radionuclides associated with colloids are unlikely to migrate downgradient from NNSS underground nuclear tests at concentrations above the SDWA MCL [4][5]. The results of over 50 years of sampling, along with an understanding of these post detonation processes, indicate that tritium is the only contaminant of concern downgradient of testing and that even tritium will not exceed its MCL in groundwater after ∼120 years. Although other longer-lived radionuclides may continue to be released slowly from the near-field environment they will likely never reach levels exceeding their MCLs in groundwater downgradient of the NNSS. Groundwater monitoring will continue to verify these observations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Modular, Mobile Systems for the Treatment of Contaminated Water at Three Magnox Sites in the United Kingdom - 20421

Veolia Nuclear Solutions (VNS), and its mitigated entity, Veolia Nuclear Solutions Federal Services (VNSFS), are designing, overseeing the fabrication and installation, and supporting the commissioning of highly mobile and modular skid-based water treatment systems to assist in the decommissioning of three Magnox reactor sites based in the U.K. These Modular Active Effluent Treatment Plants (MAETP) will be deployed at the Chapelcross, Hinkley Point A, and Dungeness A sites to process contaminated water through the use of ion exchange systems and/or filtration units. At the time of writing, two systems have been installed and inactively commissioned, and the third system is expected to be delivered in 2020. Veolia has utilized a multi-national team of engineers, based in the UK and the US, to effectively leverage the best of Veolia expertise in the design and delivery of mobile, modular systems. The VNS team continues to refine the modular, mobile, and scalable approach to water processing system delivery, and has successfully patented the evolving technology for proprietary protection. The intent of this technology investment is to improve the functionality, mobility, and modularity, resulting in a system which can be adapted to a broad range of throughput and isotope removal requirements to achieve the most cost effective, flexible system possible for customers. Designing, fabricating, and factory-testing the modules off site followed by onsite installation, testing, start-up, and commissioning ensures expedited delivery and setup, as well as cost savings for nuclear applications. For the MAETP systems, VNS's previous nuclear site experience and ongoing Research and Development (R and D), combined with the resulting mobile/modular water processing systems developed and successfully deployed by VNS, have proven to be important inputs for the successful end-design of the systems, materials selection, system testing and commissioning. The lessons learned in the development and continued enhancement of the patented systems described in this paper will prove useful in advancing and deploying future systems for other nuclear sites, where rapid customizing and cost-effective implementation are critical factors. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Development of a Testbed for Pipeline Flushing - 20425

Pipelines which carry high-level waste within the DOE complex should be properly flushed in the cases where stationary or moving beds of solid sediment occur, or lines are prone to hydrogen gas buildup. Present guidelines establish a minimum for the amount of water (flush volume) and flush velocity values used for post-transfer flushing operations to achieve satisfactory cleaning of pipelines. However, further studies are needed to find optimal operating velocity modes/values in order to minimizing the flush volume and consequent downstream waste. These efforts are significantly helpful to DOE waste remediation sites by preserving tank storage, preventing additional waste processing, and minimizing dilution and changes in waste chemistry. An experimental test loop was recently developed for study of non-Newtonian slurry flushing at the Florida International University (FIU). This loop was designed to create sediment beds of various materials and bed heights and investigate parameters that effect the efficiency of flushing operations. The objective is to find flush velocity values/modes which lead to satisfactory cleaning of transport lines with a minimum amount of water usage. A 165 ft experimental test loop made of 3-inch carbon steel pipes was constructed and used in initial testing campaigns. This pipe loop was equipped with real-time monitoring instruments to record variation of pressure, density, mass flow rate, and temperature during testing. Post-flush in-situ no-flow evaluations were performed using ultrasonic, endoscopy, and visual inspection. Additional post-flush evaluations were conducted using filtration and density monitoring of residuals within a designated circulations loop. These provisions enable comparison of pipeline cleanness before the start and after termination of flushing operations for efficiency evaluation. This paper presents efforts associated with flushing of kaolin-water mixtures at different concentrations and with various flush volume and flush velocity values/modes. In initial testing, efforts focused on creating repeatable sediment beds inside the pipeline in both fully-flooded (no pre-flush drainage) and gravity-drained (pre-flush drained) systems. Bed characterization (i.e., measurement of sediment height and solids concentration) was conducted to ensure about consistency of initial conditions between tests. Preliminary results for flushing study of 10% vol. kaolin-water mixtures starting from a fully-flooded initial condition showed that flushing with 1-line volume (65 gallons) could remove up to 72 percent of solids from the pipeline. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Update on ASME AG-1 and Revision of the DOE Nuclear Air Cleaning Handbook - 20536

The American Society of Mechanical Engineers AG-1 Code on Nuclear Air and Gas Treatment is updated every two years. This paper provides an overview of issues being discussed within AG-1 committee meetings and revisions that will be included in the next version of the code. Additional information is provided on issues being discussed ranging from media velocity limits, control of airflow using actual versus and standard cubic feet per minute. Navigation and identification of applicable high-efficiency particulate air (HEPA) filter code sections can be confusing for those unfamiliar with AG-1. A general reorganization of filtration code sections clarifies geometry, flow, and performance envelopes for nuclear grade HEPA filters. The initial step consists of establishment of Section FN covering qualification of conventional, ceramic, metal, and high strength fibrous glass media. Future filter sections are currently expected to be characterized by geometry and flow direction (axial vs. radial). The Department of Energy's (DOE) Nuclear Air Cleaning Handbook (NACH) is also undergoing revision. An update on the status of that effort, along with issues and changes being considered. The original charter of the AG-1 Code was specific to commercial nuclear power plants, and to safety-related air cleaning systems. This has evolved over the years to include normal non-safety ventilation systems and process gas systems. Corollary guidance for DOE facilities has been available in several editions of the Nuclear Air Cleaning Handbook, starting with ORNL-NSIC 65. The latest edition of the Handbook, 2003, is undergoing revision and modifications. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Visible-Light-Activated Photocatalytic Films toward Self-Cleaning Membranes

Membranes are among the most promising means of delivering increased supplies of fit-for-purpose water, but membrane fouling remains a critical issue restricting their widespread application. Coupling photocatalysis with membrane separation has been proposed as a potentially effective approach to reduce membrane fouling. However, commonly used materials in photocatalysis limit use of low-cost sources such as sunlight due to their large band gaps. There are few examples of in situ photocatalytic self-cleaning of membranes, with removal from the filtration system and ex situ illumination being more common. In this study, a visible-light-activated photocatalytic film prepared by nitrogen doping into the lattice of TiO 2 was deposited on commercial ceramic membranes via atomic layer deposition (ALD). The synergy between membrane separation and redox reactions between organic pollutants and reactive oxygen species (ROS) produced by the visible-light-activated layer offers a possibility for stable and sustainable membrane operation under in situ solar irradiation.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Freestanding Photoresist Film: A Versatile Template for Three-Dimensional Micro- and Nanofabrication

Ultrathin freestanding films with well-defined micro/nanostructures and robust mechanical properties are applied in many engineering applications including microelectronics, optics, filtration and separation, biomedical engineering, and nanotechnology. Although considerable efforts have been made toward the fabrication of freestanding thin films, it is still a significant challenge to develop a simple and reliable process for producing freestanding films with ultrathin thickness, well-regulated micro/nanopatterns, robust mechanical properties, macroscopic coverage area, and multi-layered composite structures. In this work, a significant advancement is reported in this regard. This study shows a new sacrificial-layer-free (SLF) lifting-off process, integrated with conventional micro- and nanolithography, enabling the release of micro- and nanopatterned photoresist (PR) films from the supporting substrate with unprecedented pattern coverage and structure characteristics. The freestanding PR film is resilient, can withstand significant bending and deformation, and is sufficiently flexible to be transferred onto substrates with 3D topography as a conformal soft stencil for further technological processing and applications. Moreover, the SLF lifting-off process provides a simple approach to prepare single-layered and multi-layered freestanding composite films. The results suggest that the novel SLF lifting-off process can significantly extend the capability of 3D micro-/nanofabrication.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Biocatalytic Yarn for Peroxide Decomposition with Controlled Liquid Transport

In this study, a robust biocatalytic yarn with controllable liquid transport properties is created by coating thin layers of chitosan containing catalase onto a cellulosic yarn. The resulting material integrates enzyme catalytic functionality with protective coating properties of chitosan and structural functionality of the textile. Mild immobilization conditions and good affinity between the two polysaccharides minimize enzyme inactivation during the preparation steps and prevent enzyme from leaching during peroxide decomposition testing and washing, providing a novel and versatile enzyme immobilization strategy. The catalytic efficiency of enzymes in a reaction containing solid, liquid, and gas phases is facilitated when dissolved enzyme substrate is transported by liquid flowing through the coated textile structure. The flow-through configuration decomposes at least two times more peroxide in a twenty-times smaller reaction zone volume compared to a stirred tank configuration. Liquid transport through the yarn and liquid spatial distribution within the yarn are investigated by in situ neutron radiography and neutron computed tomography, revealing a constrained wicking mechanism that benefits biocatalytic yarn performance. This new class of sustainable and flexible biocatalytic textile matrices has beneficial multifunctional properties, not previously described, that are applicable for numerous small- and large-scale applications including controlled flow reactors and reactive filtration.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The Function of Two Radical‐SAM Enzymes, HcgA and HcgG, in the Biosynthesis of the [Fe]‐Hydrogenase Cofactor

Abstract In the biosynthesis of the iron‐guanylylpyridinol (FeGP) cofactor, 6‐carboxymethyl‐5‐methyl‐4‐hydroxy‐2‐pyridinol ( 1 ) is 3‐methylated to form 2 , then 4‐guanylylated to form 3 , and converted into the full cofactor. HcgA‐G proteins catalyze the biosynthetic reactions. Herein, we report the function of two radical S ‐adenosyl methionine enzymes, HcgA and HcgG, as uncovered by in vitro complementation experiments and the use of purified enzymes. In vitro biosynthesis using the cell extract from the Methanococcus maripaludis Δ hcgA strain was complemented with HcgA or precursors 1 , 2 or 3 . The results suggested that HcgA catalyzes the biosynthetic reaction that forms 1 . We demonstrated the formation of 1 by HcgA using the 3 kDa cell extract filtrate as the substrate. Biosynthesis in the Δ hcgG system was recovered by HcgG but not by 3 , which indicated that HcgG catalyzes the reactions after the biosynthesis of 3 . The data indicated that HcgG contributes to the formation of CO and completes biosynthesis of the FeGP cofactor.

Arriaza‐Gallardo, Francisco J.↗
DOE OSTI2024

Self‐Standing Chiral Covalent Organic Framework Thin Films with Full‐Color Tunable Guest‐Induced Circularly Polarized Luminescence

Abstract Exploring self‐standing chiral covalent organic framework (COF) thin films with controllable circularly polarized luminescence (CPL) is of paramount significance but remains a challenging task. Herein, we demonstrate the first example of self‐standing chiral COF films employing a polymerization‐dispersion‐filtration strategy. Pristine, low‐quality chiral COF films were produced by interfacial polymerization and then re‐dispersed into COF colloidal solutions. Via vacuum assisted assembly, these COF colloids were densely stacked and assembled into self‐standing, pure chiral COF films ( L‐ / D‐ CCOF‐F) that were transparent, smooth, crack‐free and highly crystalline. These films were tunable in thicknesses, areas, and roughness, along with strong diffuse reflectance circular dichroism (DRCD) and cyan CPL signals, showing an intrinsic luminescence asymmetric factor ( g lum ) of ~4.3×10 −3 . Furthermore, these COF films served as host adsorbents to load various achiral organic dye guests through adsorption. The effective chiral transfer and energy transfer between CCOF‐F and achiral fluorescent dyes endowed the dyes with strong chirality and tunable DRCD, resulting in intense, full‐color‐tunable solid‐state CPL. Notably, the ordered arrangement of dye guest molecules within the preferentially oriented chiral pores of CCOF‐F contributed to an amplified | g lum | factor of up to 7.2×10 −2 , which is state‐of‐the‐art for COF‐based CPL materials. This work provides new insights into the design and fabrication of self‐standing chiral COF films, demonstrating their great potential for chiroptical applications.

Tang, Xihao↗
DOE OSTI2022

The Function of Two Radical‐SAM Enzymes, HcgA and HcgG, in the Biosynthesis of the [Fe]‐Hydrogenase Cofactor

Abstract In the biosynthesis of the iron‐guanylylpyridinol (FeGP) cofactor, 6‐carboxymethyl‐5‐methyl‐4‐hydroxy‐2‐pyridinol ( 1 ) is 3‐methylated to form 2 , then 4‐guanylylated to form 3 , and converted into the full cofactor. HcgA‐G proteins catalyze the biosynthetic reactions. Herein, we report the function of two radical S ‐adenosyl methionine enzymes, HcgA and HcgG, as uncovered by in vitro complementation experiments and the use of purified enzymes. In vitro biosynthesis using the cell extract from the Methanococcus maripaludis Δ hcgA strain was complemented with HcgA or precursors 1 , 2 or 3 . The results suggested that HcgA catalyzes the biosynthetic reaction that forms 1 . We demonstrated the formation of 1 by HcgA using the 3 kDa cell extract filtrate as the substrate. Biosynthesis in the Δ hcgG system was recovered by HcgG but not by 3 , which indicated that HcgG catalyzes the reactions after the biosynthesis of 3 . The data indicated that HcgG contributes to the formation of CO and completes biosynthesis of the FeGP cofactor.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

A comparative experimental study of the hygroscopic and mechanical behaviors of electrospun nanofiber membranes and solution–cast films of polybenzimidazole

This article reports a comparative experimental study of the hygroscopic and mechanical behaviors of electrospun polybenzimidazole (PBI) nanofiber membranes and solution-cast PBI films. As-electrospun nonwoven PBI nanofiber mats (with the nanofiber diameter of ~250 nm) were heat-pressed under controlled temperature, pressure and duration for the study; lab-made solution-cast PBI films and commercially available PBI films (the PBI Performance Product Inc., Charlotte, NC) were used as the control samples. Thermogravimetric and microtensile tests were utilized to characterize the hygroscopic (moisture absorption) and mechanical properties of the PBI nanofiber membranes at varying heat-pressing conditions, which were further compared to those of solution-cast PBI films. Experimental results indicated that the PBI nanofiber membranes carried slightly higher thermal stability and less hygroscopic properties than those of solution-cast PBI films. In addition, heat-pressing conditions significantly influenced the mechanical properties of the resulting PBI nanofiber membranes. The stiffness and tensile strength increase with increasing either the heat-pressing pressure or duration, and relevant mechanisms were explored. Here, the present study provides a rational understanding of the hygroscopic and mechanical behaviors of electrospun PBI nanofiber membranes and solution-cast PBI films that are beneficial to their reliable cutting-edge applications in high-temperature filtration, polymer electrolyte membranes (PEMs), etc.

25 ENERGY STORAGE↗
DOE OSTI2020

Highly efficient separation membrane based on cellulose acetate/chitosan fibrous composite substrate with activated carbon functional adsorption layer

Abstract BACKGROUND For improving the permeability and selectivity of adsorption separation membranes, membrane materials, structural morphology and separation technology must continue to be investigated. Development of a membrane that is environmentally friendly, cost‐effective and with high filter precision is an important direction in current research. RESULTS The air pressure spraying method was used to prepare an activated carbon (AC)–cellulose acetate/chitosan (CA/CS) composite membrane. The CA/CS fiber composite membrane was prepared as substrate layer, and AC was loaded on the surface of the CA/CS composite membrane as a functional adsorption layer. When the spraying pressure was 0.01 MPa and the mass ratio of AC/CS was 2:1, a composite membrane with even and compact morphology could be obtained. Both the compact AC functional layer and complete CA/CS substrate layer endowed the AC–CA/CS composite membrane with an excellent water filtration property. At low feeding pressure, the permeate flux and rejection rate of bisphenol A (BPA) could reach 9.27 × 10 3 L m −2 h −1 and 98.31%, respectively. Meanwhile, the adsorption capacities of the membrane were investigated. It tended to equilibrate quickly in 2 min for dyes and BPA. The equilibrium adsorption capacities of the membrane for acid blue, acid yellow and BPA were 175.80, 164.0815 and 79.58 mg g −1 , respectively. The adsorption process conformed to pseudo‐second‐order kinetics and the Langmuir monolayer adsorption model. CONCLUSIONS This work could provide a practical and effective feasibility for membrane separation technology. © 2020 Society of Chemical Industry (SCI)

Zhao, Xiaoyan↗
DOE OSTI2020

Mechanistic Models as Framework for Understanding Biomarker Disposition: Prediction of Creatinine‐Drug Interactions

Creatinine is widely used as a biomarker of glomerular filtration, and, hence, renal function. However, transporter‐mediated secretion also contributes to its renal clearance, albeit to a lesser degree. Inhibition of these transporters causes transient serum creatinine elevation, which can be mistaken as impaired renal function. The current study developed mechanistic models of creatinine kinetics within physiologically based framework accounting for multiple transporters involved in creatinine renal elimination, assuming either unidirectional or bidirectional‐OCT2 transport (driven by electrochemical gradient). Robustness of creatinine models was assessed by predicting creatinine‐drug interactions with 10 perpetrators; performance evaluation accounted for 5% intra‐individual variability in serum creatinine. Models showed comparable predictive performances of the maximum steady‐state effect regardless of OCT2 directionality assumptions. However, only the bidirectional‐OCT2 model successfully predicted the minimal effect of ranitidine. The dynamic nature of models provides clear advantage to static approaches and most advanced framework for evaluating interplay between multiple processes in creatinine renal disposition.

Scotcher, Daniel↗
DOE OSTI2021

Evaluating causal‐based feature selection for fuel property prediction models

Abstract In‐silico screening of novel biofuel molecules based on chemical and fuel properties is a critical first step in the biofuel evaluation process due to the significant volumes of samples required for experimental testing, the destructive nature of engine tests, and the costs associated with bench‐scale synthesis of novel fuels. Predictive models are limited by training sets of few existing measurements, often containing similar classes of molecules that represent just a subset of the potential molecular fuel space. Software tools can be used to generate every possible molecular descriptor for use as input features, but most of these features are largely irrelevant and training models on datasets with higher dimensionality than size tends to yield poor predictive performance. Feature selection has been shown to improve machine learning models, but correlation‐based feature selection fails to provide scientific insight into the underlying mechanisms that determine structure–property relationships. The implementation of causal discovery in feature selection could potentially inform the biofuel design process while also improving model prediction accuracy and robustness to new data. In this study, we investigate the benefits causal‐based feature selection might have on both model performance and identification of key molecular substructures. We found that causal‐based feature selection performed on par with alternative filtration methods, and that a structural causal model provides valuable scientific insights into the relationships between molecular substructures and fuel properties.

Nguyen, Bernard↗
DOE OSTI2025

Holistic Microstructure Control Strategies in Photopolymerization‐Induced Phase Separation of Acrylate Systems

Open porous materials, known for their large surface area and interconnected structures, are essential in various applications, including batteries, ion exchange, catalysis, filtration, and electronic waste recycling. A critical aspect of the functionality of porous membranes is the precise control of pore size and morphology. Photopolymerization-induced phase separation (photo-PIPS) offers a convenient and versatile methods for creating porous structures. However, controlling the porous morphology remains challenging due to the complex interplay between thermodynamics, polymerization kinetics, and monomer structures, which makes it difficult to establish the relationship between processing conditions and resulting morphology in photo-PIPS. Herein, a physics-based phase-field model capable of generating and characterizing the microstructures of porous materials based on both average and localized features is developed. Using the phase-field simulations as test bed, the effects of polarity, light intensity, and curing temperature, as well as the previously unexplored roles of chain transfer agents and substrates, on the morphology of the resulting porous microstructure are investigated. Experiments are performed to verify the results predicted by the simulations. This work lays out a comprehensive guide for designing PIPS-derived porous microstructures and offers practical engineering strategies for tailoring microstructure-level topology and size of pores for application-specific needs.

36 MATERIALS SCIENCE↗