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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

High-Lift Propeller Noise Prediction for a Distributed Electric Propulsion Flight Demonstrator

Over the past several years, the use of electric propulsion technologies within aircraft design has received increased attention. The characteristics of electric propulsion systems open up new areas of the aircraft design space, such as the use of distributed electric propulsion (DEP). In this approach, electric motors are placed in many different locations to achieve increased efficiency through integration of the propulsion system with the airframe. Under a project called Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR), NASA is designing a flight demonstrator aircraft that employs many "high-lift propellers" distributed upstream of the wing leading edge and two cruise propellers (one at each wingtip). As the high-lift propellers are operational at low flight speeds (take-off/approach flight conditions), the impact of the DEP configuration on the aircraft noise signature is also an important design consideration. This paper describes efforts toward the development of a mulit-fidelity aerodynamic and acoustic methodology for DEP high-lift propeller aeroacoustic modeling. Specifically, the PAS, OVERFLOW 2, and FUN3D codes are used to predict the aerodynamic performance of a baseline high-lift propeller blade set. Blade surface pressure results from the aerodynamic predictions are then used with PSU-WOPWOP and the F1A module of the NASA second generation Aircraft NOise Prediction Program to predict the isolated high-lift propeller noise source. Comparisons of predictions indicate that general trends related to angle of attack effects at the blade passage frequency are captured well with the various codes. Results for higher harmonics of the blade passage frequency appear consistent for the CFD based methods. Conversely, evidence of the need for a study of the effects of increased azimuthal grid resolution on the PAS based results is indicated and will be pursued in future work. Overall, the results indicate that the computational approach is acceptable for fundamental assessment of low-noise high-lift propeller designs. The extent to which the various approaches may be used in a complementary manner will be further established as measured data becomes available for validation. Ultimately, it is anticipated that this combined approach may be used to provide realistic incident source fields for acoustic shielding/scattering studies on various aircraft configurations.

Nark, Douglas M.↗
NASA NTRS2023

Development of a Photoacoustic Formaldehyde Monitor

Key indoor air quality pollutant formaldehyde (H2CO) is tracked on International Space Station (ISS) using passive badges returned to the ground periodically for analysis. The process is time-consuming both in preparation and for analysis upon return 6-12 months later. Badges also require precious crew time for deploy, retrieval and stow. As NASA’s focus in space exploration shifts to the Moon and Mars, archival sample return becomes increasingly impractical, so the aim of this project is to develop a highly reliable real-time analyzer for H2CO at low concentrations with data downlinked. Potential sources of H2CO include materials off gassing, use of formalin as a tissue fixative in biological payloads and overheating of acetal polymers. The Spacecraft Maximum Allowable Concentration (SMAC) for H2CO is 100 ppb for exposures of 7 days or longer. ISS concentrations recently run only 10 - 30 ppb but have spiked as high as 60 ppb in the past. Gateway real time monitoring requirements call for a range of 8 - 140 ppb. For this project, a concentration range of 5 - 500 ppb H2CO is targeted. The core tunable diode laser spectroscopy (TDLS) technology was developed by Vista Photonics through the NASA and US Navy Small Business Innovation Research (SBIR) programs. Monitors based on this technology have been demonstrated on ISS, trialed on a nuclear submarine and are in production as Anomaly Gas Analyzers for both ISS and Orion. Initially, direct absorption TDLS was used exclusively in these monitors, however, the H2CO target concentration is much lower, and a longer wavelength required, so a photoacoustic spectroscopy (PAS) technique was adapted, where the laser excitation is detected by a sensitive microphone vs. a conventional photodetector. This paper will discuss the results of NASA-JSC laboratory testing of a prototype PAS based formaldehyde monitor and explore potential adaptations for Gateway missions and beyond.

Paul D Mudgett↗
NASA NTRSDate not supplied

Development of a Photoacoustic Formaldehyde Monitor

Key indoor air quality pollutant formaldehyde (H 2 CO) is tracked on International Space Station (ISS) using passive badges returned to the ground periodically for analysis. The process is time-consuming both in preparation and for analysis upon return 6-12 months later. Badges also require precious crew time for deploy, retrieval and stow. As NASA’s focus in space exploration shifts to the Moon and Mars, archival sample return becomes increasingly impractical, so the aim of this project is to develop a highly reliable real-time analyzer for H 2 CO at low concentrations with data downlinked. Potential sources of H 2 CO include materials off gassing, use of formalin as a tissue fixative in biological payloads and overheating of acetal polymers. The Spacecraft Maximum Allowable Concentration (SMAC) for H 2 CO in air is 100 ppb for exposures of 7 days or longer. ISS concentrations of H 2 CO are running only 10 - 30 ppb in the recent several years but have spiked as high as 60 ppb. Gateway real time monitoring requirements for H 2 CO call for a range of 8 - 138 ppb. For this project, a concentration range of 5 - 500 ppb H 2 CO is targeted. The core tunable diode laser spectroscopy (TDLS) technology used for this project was developed by Vista Photonics through the NASA and US Navy Small Business Innovation Research (SBIR) programs. Monitors based on TDLS have been demonstrated on ISS, trialed on a nuclear submarine and are being certified as portable Anomaly Gas Analyzers (AGA) for both ISS and Orion. Initially, direct absorption TDLS was used exclusively in these devices. The H 2 CO target concentration, however, is low ppb, and a longer wavelength is required, so a photoacoustic spectroscopy (PAS) technique was adapted, where the laser excitation is detected by a sensitive microphone vs. a conventional photodetector. This paper will discuss the results of NASA-JSC laboratory testing of a prototype PAS based formaldehyde in air monitor and briefly discuss next steps.

Photoacoustic Formaldehyde Monitor↗
DOE OSTI2012

PERFORMANCE ASSESSMENT ASSISTANCE ACTIVITIES IN THE DOE COMPLEX

The United States Department of Energy Office of Environmental Management (DOE-EM) has established a Performance Assessment Community of Practice (PA CoP) to foster the sharing of information among performance assessment (PA) and risk assessment practitioners, regulators and oversight personnel. The general intent is to contribute to continuous improvement in the consistency, technical adequacy and quality of implementation of PAs and risk assessments around the DOE Complex. The PA CoP activities have involved commercial disposal facilities and international participants to provide a global perspective. The PA CoP has also sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from on-going modelling activities. The PA CoP encourages activities to provide programmatic and technical assistance in the form of sharing experience and lessons learned with practitioners during the development of PAs and risk assessments. This assistance complements DOE-EM reviews through the Low-Level Waste Disposal Facility Federal Review Group (LFRG) that are conducted after modelling efforts are completed. Such up-front assistance is providing additional value in terms of improving consistency and sharing of information. There has been a substantial increase in the amount of assistance being provided. The assistance has been well received by practitioners and regulators that have been involved. The paper highlights assistance and sharing of information that has been conducted in the last two years to support activities underway in support of proposed disposal facilities at Paducah, Portsmouth, and the Idaho National Laboratory and tank closure at Hanford.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

The Cementitious Barriers Partnership (CBP) Software Toolbox Capabilities In Assessing The Degradation Of Cementitious Barriers

The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste and Nuclear Materials Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up to 100 years and longer for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox has produced tangible benefits to the DOE Performance Assessment (PA) community. A review of prior DOE PAs has provided a list of potential opportunities for improving cementitious barrier performance predictions through the use of the CBP software tools. These opportunities include: 1) impact of atmospheric exposure to concrete and grout before closure, such as accelerated slag and Tc-99 oxidation, 2) prediction of changes in Kd/mobility as a function of time that result from changing pH and redox conditions, 3) concrete degradation from rebar corrosion due to carbonation, 4) early age cracking from drying and/or thermal shrinkage and 5) degradation due to sulfate attack. The CBP has already had opportunity to provide near-term, tangible support to ongoing DOE-EM PAs such as the Savannah River Saltstone Disposal Facility (SDF) by providing a sulfate attack analysis that predicts the extent and damage that sulfate ingress will have on the concrete vaults over extended time (i.e., > 1000 years). This analysis is one of the many technical opportunities in cementitious barrier performance that can be addressed by the DOE-EM sponsored CBP software tools. Modification of the existing tools can provide many opportunities to bring defense in depth in prediction of the performance of cementitious barriers over time.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

The Cementitious Barriers Partnership (CBP) Software Toolbox Capabilities in Assessing the Degradation of Cementitious Barriers - 13487

The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste and Nuclear Materials Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up to 100 years and longer for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox has produced tangible benefits to the DOE Performance Assessment (PA) community. A review of prior DOE PAs has provided a list of potential opportunities for improving cementitious barrier performance predictions through the use of the CBP software tools. These opportunities include: 1) impact of atmospheric exposure to concrete and grout before closure, such as accelerated slag and Tc-99 oxidation, 2) prediction of changes in K{sub d}/mobility as a function of time that result from changing pH and redox conditions, 3) concrete degradation from rebar corrosion due to carbonation, 4) early age cracking from drying and/or thermal shrinkage and 5) degradation due to sulfate attack. The CBP has already had opportunity to provide near-term, tangible support to ongoing DOE-EM PAs such as the Savannah River Saltstone Disposal Facility (SDF) by providing a sulfate attack analysis that predicts the extent and damage that sulfate ingress will have on the concrete vaults over extended time (i.e., > 1000 years). This analysis is one of the many technical opportunities in cementitious barrier performance that can be addressed by the DOE-EM sponsored CBP software tools. Modification of the existing tools can provide many opportunities to bring defense in depth in prediction of the performance of cementitious barriers over time. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Performance Assessment Program for the Savannah River Site Liquid Waste Facilities - 13610

The Liquid Waste facilities at the U.S. Department of Energy's (DOE) Savannah River Site (SRS) are operated by Liquid Waste Operations contractor Savannah River Remediation LLC (SRR). A separate Performance Assessment (PA) is prepared to support disposal operations at the Saltstone Disposal Facility and closure evaluations for the two liquid waste tank farm facilities at SRS, F-Tank Farm and H-Tank Farm. A PA provides the technical basis and results to be used in subsequent documents to demonstrate compliance with the pertinent requirements identified in operations and closure regulatory guidance. The Saltstone Disposal Facility is subject to a State of South Carolina industrial solid waste landfill permit and the tank farms are subject to a state industrial waste water permit. The three Liquid Waste facilities are also subject to a Federal Facility Agreement approved by the State, DOE and the Environmental Protection Agency (EPA). Due to the regulatory structure, a PA is a key technical document reviewed by the DOE, the State of South Carolina and the EPA. As the waste material disposed of in the Saltstone Disposal Facility and the residual material in the closed tank farms is also subject to reclassification prior to closure via a waste determination pursuant to Section 3116 of the Ronald W. Reagan National Defense Authorization Act of Fiscal Year 2005, the U.S. Nuclear Regulatory Commission (NRC) is also a reviewing agency for the PAs. Pursuant to the Act, the NRC also has a continuing role to monitor disposal actions to assess compliance with stated performance objectives. The Liquid Waste PA program at SRS represents a continual process over the life of the disposal and closure operations. When the need for a PA or PA revision is identified, the first step is to develop a conceptual model to best represent the facility conditions. The conceptual model will include physical dimensions of the closed system, both the engineered and natural system, and modeling input parameters associated with the modeled features, both initial values (at the time of facility closure) and degradation rates/values. During the development of the PA, evaluations are conducted to reflect not only the results associated with the best available information at the time but also to evaluate potential uncertainties and sensitivities associated with the modeled system. While the PA will reflect the modeled system results from the best available information, it will also identify areas for future work to reduce overall PA uncertainties moving forward. DOE requires a PA Maintenance Program such that work continues to reduce model uncertainties, thus bolstering confidence in PA results that support regulatory decisions. This maintenance work may include new Research and Development activities or modeling as informed by previous PA results and other new information that becomes available. As new information becomes available, it is evaluated against previous PAs and appropriate actions are taken to ensure continued confidence in the regulatory decisions. Therefore, the PA program is a continual process that is not just the development of a PA but seeks to incorporate new information to reduce overall model uncertainty and provide continuing confidence in regulatory decisions. (author)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Realistic Geochemical Parameter Uncertainty for Performance Assessment Modeling - 17066

Performance assessments (PAs) include uncertain geochemical parameters that affect the fate and transport of contaminants in environmental media, such as partitioning coefficients for water/rock (K{sub d}) and water/air (K{sub H}), diffusion coefficients, and aqueous solubilities. A statistical approach to realistic, as opposed to 'conservative,' stochastic distribution development for geochemical parameters is presented here. For contaminants not identified as focus elements during screening, broad generic distributions are developed. If any parameter is flagged in the subsequent model sensitivity analysis (SA), it becomes a focus element for further research during the next round of distribution development. This iterative approach is efficient and technically defensible at each stage. Data are collected in databases and may be appropriately weighted or filtered. In the relatively few cases where data exist from local or analogous rocks, those data may be prioritized. Once established, the databases can be used for future PAs or other environmental models and can be expanded as needed based on model SA results, additional screening, and as additional relevant data become available. The iterative method is demonstrated for K{sub d} and K{sub H} in a PA model for a radioactive waste disposal facility. An SA was performed based on preliminary geochemical parameter distributions that showed certain model endpoints are sensitive to K{sub d} and K{sub H} values for some contaminants. This underscores the importance of including realistic uncertainty in these geochemical parameters. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Statistical Methods for Effective Spatial and Temporal Scaling in Support of Probabilistic Performance Assessments - 17340

Performance assessments (PAs) for the disposal of low-level radioactive waste have traditionally been performed in a deterministic manner, with inputs specified as single values as if they carry no uncertainty. Modern PAs, however, explicitly incorporate uncertainty through use of probability distributions for inputs instead of single values. While this is clearly an improvement, challenges remain in specifying appropriate distributions, many of which relate to capturing the appropriate spatial and/or temporal scale given the PA model, and matching the scale(s) of data and information to that specified by the model. More careful attention to scaling will lead to more defensible characterizations of physical variability and uncertainty in model inputs, thus leading to more defensible information regarding outcomes of interest to be used in decision making, and hence more defensible decisions. This work introduces general strategies and considerations for explicitly incorporating considerations of scale into distribution development. The strategies are explained as a series of steps and then presented with an example that starts to illustrate the new statistical concepts. This work frames the problem in terms of hierarchical statistical modeling, providing important connections to current statistical approaches to formally and rigorously account for temporal and spatial scaling. The larger goal is to build a more formal and unified approach to distribution development to help teams of modelers, subject matter experts, and statisticians work together to develop distributions and justify the choices made in the process, ultimately leading to more informed decision-making. Without this rigor, statistical distributions are not specified correctly and can have unexpected consequences for modeling and sensitivity analysis. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

A Multiple Lines of Evidence Approach for Conceptual Site Models in Performance Assessments - 19070

Demonstration of the long-term performance of remediated radioactive waste sites relies on models that evaluate vadose zone and groundwater flow and contaminant transport for thousands of years. Model qualification, verification, and comparisons with data are essential elements to demonstrating the accuracy of long-term performance assessments (PAs). However, comparisons with data are generally limited due to incomplete characterization data and long-time scales. Since PAs support decision making to assure long-term protection of both human health and the environment, a conceptual site model (CSM) is needed to explain the hydrodynamic behavior and account for subsurface heterogeneities in sufficient detail to support confident decisions. In the case of the Waste Management Area (WMA) C PA, where the focus of the effort is on characterizing flow and transport through a thick vadose zone, site-specific data are sparse and larger-scale geologic descriptions are adopted with the risk of losing small scale features that may affect contaminant transport. Features such as horizontal bedding and sloping interfaces between contrasting material types, as well as vertically oriented features such as clastic dikes, may be difficult to delineate from sparse characterization data, but may affect the extent to which contaminants are transported. The PA conducted to identify long-term impacts associated with the closure of the single-shell tank (SST) farm at WMA C adopted an equivalent homogenous medium approach to represent the major stratigraphic units at the site. This approach explicitly represents major stratigraphic units but assigns hydraulic properties that implicitly account for the presence of small-scale heterogeneities and their impact on flow and contaminant transport to the groundwater. The objective of this study is to evaluate the available site-specific and analogue data that can be used to characterize heterogeneity and to assess its impact on fate and transport of contaminants that may lead to different conclusions when compared to the results of the equivalent homogeneous media approach. To this end, a multiple lines of evidence approach was used to construct alternative CSMs based on an evaluation of several types of data. These data include 1) general characteristics and features of the major stratigraphic units from historical descriptions; 2) borehole geologic logs; 3) particle size distribution measurements; 4) moisture content measurements; 5) spectral gamma data; and 6) concentrations of key constituents (i.e., Tc-99) in both the vadose zone and groundwater impacted by past releases. Based on an analysis of the available data, lines of evidence are evaluated for consistency and integrated in a consistent manner into scientifically defensible CSMs. Numerical models are then used to evaluate the impact that the explicit representation of heterogeneities has on contaminant transport. Together, the field data and the numerical modeling results indicate that heterogeneity caused by the small-scale features do not have a significant (i.e. greater than a factor of 2) impact on transport below WMA C relative to peak concentrations and arrival times for potential releases from waste tanks. The results of this study underscore the value of using multiple lines of evidence based on the quantity and quality of available data in developing alternative CSMs and evaluating their relative impact on key transport metrics such as arrival times and peak concentration. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Reaction Optimization for Enzymatic Deconstruction of Industrially Relevant Nylon Composites

Plastics such as polyamides (PAs) possess unique physicochemical properties that make them indispensable in modern society. However, their energy‐intensive production and challenging end‐of‐life management highlight the urgent need for efficient recycling or remanufacturing solutions. Enzymatic depolymerization offers a promising route toward circular recycling, yet remains constrained by limited enzyme characterization, lack of validation under industrially relevant conditions and substrates, and overall performance. Here, we optimized the reaction conditions for three recently discovered nylon‐degrading enzymes. One of them, Nyl12, achieved product titers with PA6 and PA66 that exceed previously reported values, without enzyme engineering or substrate pretreatment. We further demonstrated the scalability of the process and its application to complex PA‐based materials used in microelectronic components. Analysis of substrate features, including surface area and particle size, revealed key parameters governing enzymatic activity and provided a framework for future pretreatment and process optimization efforts. In combination, these efforts provide a new benchmark for enzymatic nylon recycling.

nylon↗
DOE OSTI2025

Hydrolysis of Polyamide 6 to ε‐Caprolactam over Titanium Dioxide

Polyamides (PAs) are an important component of discarded textiles and food packaging. Chemical recycling can recover PA monomers, enabling repolymerization to produce virgin-grade PA. However, contemporary PA chemical recycling methods employ homogeneous catalysts that are hard to separate. Anatase TiO 2 is reported as a catalyst for PA6 hydrolysis at 270 °C for 0.5 h, achieving a maximum ε-caprolactam (CL) yield of 81% (limited by thermodynamic equilibrium). The CL yield decreases upon catalyst reuse, due to loss of catalyst surface area induced by significant changes in catalyst crystallinity and texture. Pretreating the catalyst hydrothermally stabilizes it against morphological changes, yielding repeatable CL yields. Altogether, this study discloses a heterogeneous catalyst capable of producing repeatable equilibrium CL yields via PA6 hydrolysis under industrially relevant reaction temperatures and times (<3 h, 250–330 °C).

depolymerization↗
DOE OSTI2013

Use of {sup 99m}Tc 2-methoxyisobutyl isonitrile in minimally invasive radioguided surgery in patients with primary hyperparathyroidism: A narrative review of the current literature

The use of technetium-99m 2-methoxyisobutyl isonitrile ({sup 99m}Tc MIBI) for assistance in minimally invasive radioguided surgery (MIRS) is growing in popularity as a safe, effective, and proficient technique used for parathyroidectomy in primary hyperparathyroidism (PHPT) treatment. Previously, the preferred treatment for PHPT was bilateral neck exploration (BNE), a very invasive, costly, and lengthy procedure. However, as a large majority (80–85% of cases of PHPT) are attributed to a single parathyroid adenoma (PA), a simpler more direct technique such as MIRS is a far better option. The following article is an exploration of the current literature concerning varied protocols utilizing {sup 99m}Tc MIBI for assistance in MIRS for patients undergoing treatment of PHPT. This technique boasts many advantageous outcomes for patients suffering from PHPT. These include a reduction in cost, operating time, and patient recovery; less evidence of post-surgical hypocalcaemia, less pain, and complications; superior cosmetic results; same-day discharge; and the possibility of local anaesthesia which is particularly beneficial in elderly patients. Better outcomes for patients with deep or ectopic PAs, reduced intra-operative complications, and improved cosmetic outcomes for patients who have previously undergone thyroid and/or parathyroid surgery are also advantageous. Of the literature reviewed it was also found that no patients suffered any major surgical complications such as laryngeal nerve palsy or permanent hypoparathyroidism using {sup 99m}Tc MIBI for assistance in MIRS.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Thylakoid-integrated recombinant Hcf106 participates in the chloroplast twin arginine transport system

The chloroplast twin arginine transport (cpTat) system distinguishes itself as a protein transport pathway by translocating fully folded proteins, using the proton-motive force (PMF) as the sole source of energy. The cpTat pathway is evolutionarily conserved with the Tat pathway found in the plasma membrane of many prokaryotes. The cpTat (Escherichia coli) system uses three proteins, Tha4 (TatA),Hcf106 (TatB), and cpTatC (TatC), to form a transient translocase allowing the pas-sage of precursor proteins. Briefly, cpTatC and Hcf106, with Tha4, form the initial receptor complex responsible for precursor protein recognition and binding in an energy-independent manner, while a separate pool of Tha4 assembles with the pre-cursor-bound receptor complex in the presence the PMF. Analysis by blue-native polyacrylamide gel electrophoresis (BN-PAGE) shows that the receptor complex, in the absence of precursor, migrates near 700 kDa and contains cpTatC and Hcf106with little Tha4 remaining after detergent solubilization. To investigate the role thatHcf106 may play in receptor complex oligomerization and/or stability, systematic cysteine substitutions were made in positions from the N-terminal transmembrane domain to the end of the predicted amphipathic helix of the protein. BN-PAGE analysis allowed us to identify the locations of amino acids in Hcf106 that were critical for interacting with cpTatC. Oxidative cross-linking allowed us to map interactions of the transmembrane domain and amphipathic helix region of Hcf106. In addition, we showed that in vitro expressed, integrated Hcf106 can interact with the precursor signal peptide domain and imported cpTatC, strongly suggesting that a subpopulation of the integrated Hcf106 is participating in competent cpTat complexes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Wholly Heterocycles-Based Polyamide–Sulfide Containing Pyridine and Thiazole Rings: A Super-Adsorbent Polymer for Lead Removal

Wholly heterocycles-based polyamide-sulfide (PAS) containing pyridine and thiazole rings with thioether linkage was synthesized and used as a novel adsorbent for lead ion removal from water. The polymer adsorbent was fully characterized via FTIR, NMR and scanning electron microscopy (SEM). The thermal properties of the synthesized polyamide were also studied by thermogravimetric analysis and the outcome showed that the polymer has a good to moderate thermal stability. The SEM was used to investigate the morphology of the wholly heterocycles-based polyamide and the outcomes displayed a porous and globular-like morphology, which guarantee effective metal adsorption. Pb(II) ion removal capacity of the synthesized polymer was studied by varying the contact time and the adsorbent concentration. The maximum removal of Pb(II) was obtained as 99%. Equilibrium behavior and kinetic of the adsorption were also investigated using prevalent isotherm and kinetic models. The adsorption capacity was obtained to be around 714 mg g{sup −1}. The Langmuir isotherm and the pseudo-second order kinetic model suggested superior agreement with the equilibrium and kinetic adsorption data, respectively. Generally, the results of this research demonstrated that the synthesized polymer is a super-adsorbent for heavy metal removal from water.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Bio-based PA5.10 for Industrial Applications: Improvement of Barrier and Thermo-mechanical Properties with Rice Husk Ash and Nanoclay

Composites consisting of renewable PA5.10 were obtained from melt compounding with a modified clay (CL) and/or a by-product obtained from the combustion of rice husk (RHA). Two different industrialized lab-scale machines were used to obtain the final shape: a film extrusion machine and an injection moulding apparatus. The industrial application requirements for polyamides generally need good barrier properties and high thermo-mechanical strength. Considering the barrier properties, the CL was able to decrease the oxygen permeability to less than half with respect to neat PA5.10. DMTA demonstrated that the addition of RHA caused a consistent enhancement (+ 46 °C) in the heat deflection temperature (HDT) compared to the neat PA5.10 matrix, increasing the possible areas of interest. Furthermore, the simultaneous presence of RHA and CL provided the best result reaching an extraordinary HDT of 131 °C. A complete discussion taking into account the morphology, crystallinity and filler-matrix adhesion evaluation was reported as well as comparison of performances with other bio-PAs composites. These two fillers can therefore be used separated or together combined in PA5.10 for functional purposes in a sustainable scenario.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Infections in patients using ventricular-assist devices: Comparison of the diagnostic performance of {sup 18}F-FDG PET/CT scan and leucocyte-labeled scintigraphy

Background: The usage of left-ventricular-assist device (LVAD) is increasing in patients presenting with advanced heart failure. However, device-related infections are a challenge to recognize and to treat, with an important morbidity and mortality rate. The role of nuclear medicine imaging remains not well established for LVAD infections. The present study compared the accuracy of positron emission tomography/computed tomography with {sup 18}F-fludeoxyglucose ({sup 18}F-FDG PET/CT) and radiolabeled leucocyte scintigraphy for the diagnosis of infections in patients supported with a continuous-flow LVAD. Methods: From a prospectively maintained database, we retrospectively analyzed the diagnostic performance of radiolabeled leucocyte scintigraphy and {sup 18}F-FDG PET/CT in 24 patients who had a LVAD with a suspected device-related infection. Both examinations were routinely performed in all patients. Infection was assessed by the International Society for Heart and Lung Transplantation criteria. Results: Twenty-four patients were included: 15 had a specific VAD infection (5 cardiac-LVAD and 10 driveline), 6 had a VAD-related infection, while 3 patients had a non-VAD-related infection. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 95.2%, 66.7%, 95.2%, 66.7%, and 91.6%, respectively, for {sup 18}F-FDG-PET; and 71.4%, 100%, 100%, 33.3%, and 75%, respectively, for leucocyte scintigraphy. {sup 18}F-FDG PET/CT showed significantly higher sensitivity (P = 0.01) than leucocyte scintigraphy. Conclusion: {sup 18}F-FDG PET/CT and radiolabeled leucocyte scintigraphy single-photon emission computed tomography carry high performance in the diagnostic of LVAD infections. {sup 18}F-FDG PET/CT shows significantly higher sensitivity and could be proposed as first-line nuclear medicine procedure. [French] French Abstract: Contexte: L’utilisation du dispositif d’assistance ventriculaire gauche (DAVG) est en utilisation croissante chez les patients avec insuffisance cardiaque avancée. Cependant, les infections liées au dispositif sont un défi à reconnaître et à traiter en raison d’ un taux de morbidité et de mortalité important. Le rôle de l’imagerie de médecine nucléaire n’est pas encore bien établi pour les infections secondaires au DAVG. La présente étude compare la précision de la tomographie par émission de positrons / tomodensitométrie au 18F-fluorodéoxyglucose (18F-FDG TEP/TDM) et la scintigraphie leucocytaire radio-marquée pour le diagnostic d’infections chez des patients porteurs par un DAVG à flux continu. Méthodes: A partir d’une base de données complétée de manière prospective nous avons analysé rétrospectivement les performances diagnostiques de la scintigraphie leucocytaire radio-marquée et de la TEP / TDM au 18F-FDG chez 24 patients ayant un DAVG avec une infection suspectée liée à l’appareillage. Les deux types d’examens scintigraphiques ont été systématiquement réalisé chez tous les patients. Le diagnostic d’infection fut établi selon les critères ISHLT. Résultats: Parmi les 24 patients inclus, 15 avaient une infection spécifique de l’appareillage AVG (5 au niveau de la pompe et/ou canule d’insertion myocardique) et 10 au niveau du driveline, 6 avaient une infection indirectement liée à l’appareillage AVG, tandis que 3 patients avaient une infection non liée au DAVG. La sensibilité, la spécificité, la valeur prédictive positive, la valeur prédictive négative et la précision étaient de 95,2%, 66,7%, 95,2%, 66,7% et 91,6%, respectivement, pour le 18F-FDG-PET et 71,4%, 100%, 100%, 33,3 %, et 75%, respectivement, pour la scintigraphie leucocytaire. La TEP / TDM au 18F-FDG a montré une sensitivité significativement plus élevée (p = 0,01) que la scintigraphie leucocytaire. Conclusion: 18F-FDG TEP/TDM et scintigraphie leucocytaire radio-marquée SPECT s’avèrent très efficaces pour le diagnostic des infections à DVAG. La TEP/TDM au 18F-FDG montre une sensibilité significativement plus élevée et pourrait être proposée en tant que la procédure de médecine nucléaire de premier choix. [Spanish] Spanish Abstract: Antecedentes: El uso de dispositivos de asistencia ventricular izquierda (DAVI) está incrementando en pacientes con insuficiencia cardiaca avanzada. Sin embargo, las infecciones relacionadas al dispositivo representan un reto diagnóstico y de tratamiento, con una importante tasa de morbilidad y mortalidad. El papel de los estudios de imagen de medicina nuclear en las infecciones de DAVI no se ha establecido claramente. El presente estudio comparó la precisión de la tomografía por emisión de positrones/tomografía computada con {sup 18}F-fluorodesoxiglucosa ({sup 18}F-FDG PET/CT) y la gammagrafía con leucocitos marcados para el diagnóstico de infecciones en pacientes utilizando un DAVI de flujo continuo. Métodos: Desde una base de datos obtenida de manera prospectiva, analizamos de manera retrospectiva el rendimiento diagnóstico de la gammagrafía de leucocitos marcados y del {sup 18}F-FDG PET/CT en 24 pacientes quienes tenían un DAVI con sospecha de infección relacionada al dispositivo. Ambos estudios fueron realizados rutinariamente en todos los pacientes. Se determinó la presencia de infección mediante los criterios de la ISHTL. Resultados: Se incluyeron veinticuatro pacientes, de los cuales 15 tuvieron una infección específica de DAV (5 con infecciones DAVI, y 10 con infección del driveline), 6 tuvieron una infección relacionada al DAV, y 3 pacientes tuvieron una infección no relacionada al DAV. La sensibilidad, especificidad, valor predictivo positivo, valor predictivo negativo y precisión diagnóstica fueron 95.2%, 66.7%, 95.2%, 66.7% y 91.6%, respectivamente para {sup 18}F-FDG PET/CT, y 71.4%, 100%, 100%, 33.3% y 75%, respectivamente para la gammagrafía de leucocitos marcados. El {sup 18}F-FDG PET/CT mostró una significativa mayor sensibilidad (p=0.01) que la gammagrafía con leucocitos marcados. Conclusión: El {sup 18}F-FDG PET/CT y la gammagrafía de leucocitos marcados tienen un alto desempeño en el diagnóstico de infecciones de DAVI. El {sup 18}F-FDG PET/CT muestra una significativa mayor sensibilidad y podría ser propuesto como el procedimiento de medicina nuclear de primera línea. [Chinese] Chinese Abstract: 背景: 左心室辅助装置 (LVAD) 越来越多的应用于重度心力衰竭患者。然而, 设备相关的感染有着重要的发病率和死亡率, 并且对其诊断和治疗均是一项挑战。对于 LVAD 相关感染, 核医学影像可扮演的角色一直没有完善。本研究针对装备有连续流式 LVAD 的感染病人,对比了 {sup 18}F-FDG PET/CT 造影术和放射性标记白细胞闪烁扫描法对感染诊断的准确性。 方法: 从一个前瞻性的数据库, 入选了24名疑似设备感染的 LVAD 病人, 并回顾性的分析了放射性标记白细胞闪烁扫描法和 {sup 18}F-FDG PET/CT 的诊断表现。所有病人都常规进行了上述两种检查。利用 ISHLT 标准对感染情况进行评估。 结果: 在入选的 24 名病人中, 15 名有明确的 VAD 感染 (5 名心脏的 LVAD 和 10 名动力传动系统装置), 6 名有 VAD 相关的感染,另外3名有 VAD 无关的感染。对于 {sup 18}F-FDG PET/CT 诊断方法,其敏感性,特异性,阳性预测值,阴性预测值和准确率分别为: 95.2%, 66.7%, 95.2%, 66.7%, 和 91.6%; 而对于白细胞闪烁扫描诊断方法, 其敏感性, 特异性, 阳性预测值,阴性预测值和准确率分别为: 71.4%, 100%, 100%, 33.3% 和 75%。相比于白细胞闪烁扫描, {sup 18}F-FDG PET/CT 明显展现出较高的敏感性 (p=0.01)。 结论: {sup 18}F-FDG PET/CT 和白细胞闪烁扫描 SPECT 对于 LVAD 感染的诊断具有很好的表现。{sup 18}F-FDG PET/CT 展现出较高的敏感性,可以作为核医学的首要检查。.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Silencing NPAS2 promotes cell growth and invasion in DLD-1 cells and correlated with poor prognosis of colorectal cancer

Highlights: • NPAS2 mRNA was down-regulated in clinical colorectal cancer tissues. • Low NPAS2 level was associated with the tumor size, TNM stage and distance metastasis in CRC. • Silencing NPAS2 promoted cell proliferation, the wound healing and cell invasion abilities. - Abstract: Emerging evidences show that circadian rhythm disorder is an important factor of tumor initiation and development. Neuronal PAS domain protein2 (NPAS2), which is the largest circadian gene, has been proved to be a novel prognostic biomarker in breast cancer and non-Hodgkin’s lymphoma. However, the potential functions of NPAS2 in colorectal cancer are still unknown. In our present study, we detected the mRNA expressions of NPAS2 in 108 CRC patients by RT-PCR, and found that NPAS2 expression was significantly down-regulated in tumor tissues than that in NATs. Clinicopathologic analysis revealed that low expression of NPAS2 was associated with the tumor size, TNM stage and tumor distance metastasis in colorectal cancer (p < 0.05). Furthermore, we effectively down-regulated NPAS2 mRNA expression by transfecting RNA interfere fragments into DLD-1 cells, and our results in vitro demonstrated that silencing NPAS2 expression could promote cell proliferation, cell invasion and increase the wound healing ability (p < 0.05). However, down-regulating NPAS2 expression did not influence the apoptotic rate in DLD-1 cells (p > 0.05). In conclusion, our study suggested that NPAS2, functioned as a potential tumor suppressor gene, could serve as a promising target and potential prognostic indicator for colorectal cancer.

60 APPLIED LIFE SCIENCES↗