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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Characterising Encapsulated Nuclear Waste using Cosmic-ray Muon Tomography (MT)

A prototype scintillating-fibre detector system has been developed at the University of Glasgow in collaboration with the UK National Nuclear Laboratory (NNL) for the nondestructive assay of UK legacy nuclear waste containers. This system consists of four tracking modules, two above and two below the container under interrogation. Each module consists of two orthogonal planes of 2 mm-pitch fibres yielding one space point. Per plane, 128 fibres are read out by a single Hamamatsu H8500 64-channel MAPMT with two fibres multiplexed onto each pixel. The configuration allows the reconstruction of the incoming and scattered muon trajectories, thus enabling the container content, with respect to atomic number Z, to be determined. Results are shown from experimental data collected for high-Z objects within an air matrix and within a shielded, concrete-filled container. These reconstructed images show clear discrimination between the low, medium and high-Z materials present, with dimensions and positions determined with sub-centimetre precision. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

SU-E-T-211: Induced Release of Nanocarrier Encapsulated Chemotherapeutic Drugs Using Proton Radiotherapy Beams

Purpose: The purpose of this work was to develop and validate an open source independent MU dose calculation software for S and S IMRT based in the algorithm proposed by Kung et.al. Methods: Treatment plans were done using Iplan v4.5 BrainLAB TPS and S and S IMRT modality. A 6MV photon beam produced by a Primus linear accelerator equipped with an Optifocus MLC was used. TPS dose calculation algorithms were pencil beam and Monte Carlo. 230 IMRT treatments plans were selected for the study. The software was written under MALTLAB environment. Treatment plans were imported by the software using RTP format. Field fluences were reconstructed adding all segments.The algorithm implemented in the software calculates the dose at a reference point as the sum of primary and scatter dose. The primary dose is obtained by masking the fluence map with a circle of radius 1cm. The scatter dose is obtained through a shaped ring mask around the previous circle with a thickness of 0.5cm; the rings are increased one after another with constant thickness until cover the entire map of influence. The dosimetric parameters Sc, Sp and TPR vary depending on radio, the transmission effect of the MLC, inverse square law and dose profile are used for the calculation. Results: The average difference between measured and independent calculated dose was 0.4% ± 2.2% [−6.8%, 6.4%]. For 91% of the studied plans the difference was less than 3%. The difference between the measured and TPS dose with pencilbeam algorithm was 2.6% ± 1.41% [−2.0%, 5.6%] and Monte Carlo algorithm was 0.4% ± 1.5% [−4.9%, 3.7%]. The differences obtained are comparable to that obtained with the ionization chamber and TPS. Conclusion: The developed software is suitable for use in S and S IMRT dose calculation. This application is open and can be downloading under request.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Formation of Vortex Flows in Liquid Crystal Phases Encapsulated in Microliter Volumes under the Action of Focused Laser Radiation

A theoretical description of the process of formation of vortex flows v(t, r) and the evolution of the director field n̂ in microliter liquid crystal (LC) volumes with a free surface under the influence of a temperature gradient ∇T(t, r), which is initiated by focused laser radiation, has been proposed. Thermomechanical contributions to both the stress tensor and viscous moment which are acting per unit volume of the LC phase were taken into account in the framework of the nonlinear generalization of the classical Ericksen−Leslie theory, which allowed describing the origin and formation of vortex flows in nematics formed by 4-n-pentyl- 4'-cyanobiphenyl molecules. Various hydrodynamic modes of vortex formation in microsized LC volumes under the action of focused laser radiation have been investigated by numerical methods.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

RAJA - LLNL HPC Architecture Portability Encapsulation Layer Version 1.0

RAJA is a collection of C++ software abstractions designed to make HPC applications portable across a range of hardware architectures and programming models. The main conceptual abstraction in FAJA is a loop. RAJA provides abstractions for types, loop execution and scheduling, and loop iteration space portioning and ordering cooperate to insulate algorithms in application code that domain experts write from implementations details of those algorithms that may need to depend on the underlying computer hardware for high performance.

ECP↗
DOE OSTI2014

Growth of Chlamydomonas reinhardtii in acetate-free medium when co-cultured with alginate-encapsulated, acetate-producing strains of Synechococcus sp. PCC 7002

The model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. We demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC7002.

09 BIOMASS FUELS↗
DOE OSTI2014

Neutronics Studies of Uranium-bearing Fully Ceramic Micro-encapsulated Fuel for PWRs

Our study evaluated the neutronics and some of the fuel cycle characteristics of using uranium-based fully ceramic microencapsulated (FCM) fuel in a pressurized water reactor (PWR). Specific PWR lattice designs with FCM fuel have been developed that are expected to achieve higher specific burnup levels in the fuel while also increasing the tolerance to reactor accidents. The SCALE software system was the primary analysis tool used to model the lattice designs. A parametric study was performed by varying tristructural isotropic particle design features (e.g., kernel diameter, coating layer thicknesses, and packing fraction) to understand the impact on reactivity and resulting operating cycle length. Moreover, to match the lifetime of an 18-month PWR cycle, the FCM particle fuel design required roughly 10% additional fissile material at beginning of life compared with that of a standard uranium dioxide (UO 2 ) rod. Uranium mononitride proved to be a favorable fuel for the fuel kernel due to its higher heavy metal loading density compared with UO 2 . The FCM fuel designs evaluated maintain acceptable neutronics design features for fuel lifetime, lattice peaking factors, and nonproliferation figure of merit.

10 SYNTHETIC FUELS↗
DOE OSTI2021

Enhanced radiative and thermal properties from surface encapsulation of InAs nanowires

In this work, photoluminescence (PL), quantum efficiency and carrier dynamics are investigated in indium arsenide (InAs) nanowires (NWs) with various surface treatments, including a molecular beam epitaxy (MBE)-grown semiconductor shell passivation, sulfur-passivation, alumina (Al 2 O 3 ) coating by atomic layer deposition (ALD) and polydimethylsiloxane (PDMS) spin-coating. The ALD-dielectric layer-coated InAs core-shell NWs show a maximum 13-fold increase in PL intensity. In contrast to the previous reports, this enhancement is found to be due to increased radiative rate from an enhanced Purcell factor, better thermal conductance and higher carrier injection within the NWs instead of improved surface quality. Numeric simulations confirm the experimentally observed increased radiative rate. Further improvements are suggested with even thicker capped InAs NWs. Carrier lifetime in surface-treated NWs is extended and shows long-term stability, critical for practical devices.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Modeling and Validation of the Thermal Response of TDI Encapsulating Foam as a function of Initial Density

TDI foams of nominal density from 10 to 45 pound per cubic foot were decomposed within a heated stainless steel container. The pressure in the container and temperatures measured by thermocouples were recorded with each test proceeding to an allowed maximum pressure before venting. Two replicate tests for each of four densities and two orientations in gravity produced very consistent pressure histories. Some thermal responses demonstrate random sudden temperature increases due to decomposition product movement. The pressurization of the container due to the generation of gaseous products is more rapid for denser foams. When heating in the inverted orientation, where gravity is in the opposite direction of the applied heat flux, the liquefied decomposition products move towards the heated plate and the pressure rises more rapidly than in the upright configuration. This effect is present at all the densities tested but becomes more pronounced as density of the foam is decreased. A thermochemical material model implemented in a transient conduction model solved with the finite element method was compared to the test data. The expected uncertainty of the model was estimated using the mean value method and importance factors for the uncertain parameters were estimated. The model that was assessed does not consider the effect of liquefaction or movement of gases. The result of the comparison is that the model uncertainty estimates do not account for the variation in orientation (no gravitational affects are in the model) and therefore the pressure predictions are not distinguishable due to orientation. Temperature predictions were generally in good agreement with the experimental data. Predictions for response locations on the outside of the can benefit from reliable estimates associated with conduction in the metal. For the lighter foams, temperatures measured on the embedded component fall well with the estimated uncertainty intervals indicating the energy transport rate through the decomposed region appears to be accurately estimated. The denser foam tests were terminated at maximum allowed pressure earlier resulting in only small responses at the component. For all densities the following statements are valid: The temperature response of the embedded component in the container depends on the effective conductivity of the foam which attempts to model energy transport through the decomposed foam and on the stainless steel specific heat. The pressure response depends on the activation energy of the reactions and the density of the foam and the foam specific heat and effective conductivity. The temperature responses of other container locations depend heavily on the boundary conditions and the stainless steel conductivity and specific heat.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Engineering a therapeutic microbe for site-of-infection delivery of encapsulated antimicrobial peptides (AMPs)

Antimicrobial peptides (AMPs) are promising therapeutics against antibiotic resistant pathogens, but they are difficult to administer at the site of infection due to poor stability. To enhance the stability of AMPs for effective and specific delivery at a site of infection, this project aimed to develop components of a novel, cell-based, drug delivery platform for AMPs in which a therapeutic microbe is engineered to specifically detect a pathogen of interest and effectively release AMPs at high, local concentrations in response. We focused the majority of our project on developing a system to produce normally host-toxic AMPs in our model therapeutic microbe (Escherichia coli) in high quantities using a protein cage system called an encapsulin (Enc) nanocompartment system. We were able to successfully produce an AMP called HBCM2 (HB), which is effective in killing our model pathogen, Pseudomonas aeruginosa, in E. coli by fusing it to an engineered, non-cage forming Enc protein, which prevented its toxicity to the E. coli. This engineered Enc protein could then be digested by a specific protease (TEV protease) for release of HB when desired. In addition to the HB production system, we also constructed a preliminary engineered E. coli capable of sensing P. aeruginosa via its specific quorum-sensing molecule, producing HB peptide, and releasing it via self-lysis in response. Preliminary characterization of this system was conducted, but we hope to fully characterize the system in future studies. The overall results produced from this study demonstrate the power of synthetic biology to confer novel functions on cells for biomanufacturing and therapeutic applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Thermal Decomposition of Mixed Foams used as Encapsulant Materials

Decomposition profiles for individual and mixed foam samples were examined in partially confined and unconfined environments. The weight percent loss versus temperature plots for the individual and mixed foams show that foams in a partially confined environment experience decomposition at a higher onset temperature than do foams in an unconfined environment. Likewise, the decomposition profiles of foams and mixed foams in a partially con fined environment differed from the decomposition profiles of these materials in an unconfined environment. These results suggest that different environments affect the decomposition mechanisms of foams. Furthermore, derivative thermogravimetric analysis showed that mixed foam samples decompose differently than do their individual parts, indicating that a foam will undergo a different mechanism of decomposition when heated in the presence of other foams than when heated alone.

36 MATERIALS SCIENCE↗