Results for “CEOS” — Page 44

DOE OSTI2016

TH-D-BRC-00: Educational Point Counter/Point: Has Photon RT Hit the Limits?

Interest in proton therapy has increased dramatically in the past couple of years, especially in the United States. There certainly is an important place for proton therapy in the arsenal of cancer treatments. Its dosimetric advantage and potential for low toxicity makes it the perfect partner for photons and other cancer treatment modalities. Often there is a belief that the new technology ought to be better but many believe that they should be widely adopted in the clinic only after evidence has shown that they are at least as safe and efficacious as existing technologies, which are often less expensive. This is the case for proton radiotherapy. This session being both educational and debate will provide a good review of basics and technological advancement as well as a comprehensive clinical update for both proton and photon therapy. Future technology developments and how they will impact the potential dosimetric advantage of proton therapy will be discussed. Particularly the debate will focus on whether these developments will close or widen the gap between photon and proton therapy. Learning Objectives: To review challenges, limitations, and recent and future developments in proton therapy. To review challenges, limitations, recent and future developments in photon radiotherapy. To review current clinical trials and challenging clinical cases. C. Yu, No company or organization that my presentation mentions provided me with financial support. I am the Founder and CEO of Xcision Medical Systems, LLC. However, my presentation will not mention any product or technology developed by Xcision.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

TH-D-BRC-01: Panel Member

Interest in proton therapy has increased dramatically in the past couple of years, especially in the United States. There certainly is an important place for proton therapy in the arsenal of cancer treatments. Its dosimetric advantage and potential for low toxicity makes it the perfect partner for photons and other cancer treatment modalities. Often there is a belief that the new technology ought to be better but many believe that they should be widely adopted in the clinic only after evidence has shown that they are at least as safe and efficacious as existing technologies, which are often less expensive. This is the case for proton radiotherapy. This session being both educational and debate will provide a good review of basics and technological advancement as well as a comprehensive clinical update for both proton and photon therapy. Future technology developments and how they will impact the potential dosimetric advantage of proton therapy will be discussed. Particularly the debate will focus on whether these developments will close or widen the gap between photon and proton therapy. Learning Objectives: To review challenges, limitations, and recent and future developments in proton therapy. To review challenges, limitations, recent and future developments in photon radiotherapy. To review current clinical trials and challenging clinical cases. C. Yu, No company or organization that my presentation mentions provided me with financial support. I am the Founder and CEO of Xcision Medical Systems, LLC. However, my presentation will not mention any product or technology developed by Xcision.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

TH-D-BRC-02: Panel Member

Interest in proton therapy has increased dramatically in the past couple of years, especially in the United States. There certainly is an important place for proton therapy in the arsenal of cancer treatments. Its dosimetric advantage and potential for low toxicity makes it the perfect partner for photons and other cancer treatment modalities. Often there is a belief that the new technology ought to be better but many believe that they should be widely adopted in the clinic only after evidence has shown that they are at least as safe and efficacious as existing technologies, which are often less expensive. This is the case for proton radiotherapy. This session being both educational and debate will provide a good review of basics and technological advancement as well as a comprehensive clinical update for both proton and photon therapy. Future technology developments and how they will impact the potential dosimetric advantage of proton therapy will be discussed. Particularly the debate will focus on whether these developments will close or widen the gap between photon and proton therapy. Learning Objectives: To review challenges, limitations, and recent and future developments in proton therapy. To review challenges, limitations, recent and future developments in photon radiotherapy. To review current clinical trials and challenging clinical cases. C. Yu, No company or organization that my presentation mentions provided me with financial support. I am the Founder and CEO of Xcision Medical Systems, LLC. However, my presentation will not mention any product or technology developed by Xcision.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

TH-D-BRC-03: Panel Member

Interest in proton therapy has increased dramatically in the past couple of years, especially in the United States. There certainly is an important place for proton therapy in the arsenal of cancer treatments. Its dosimetric advantage and potential for low toxicity makes it the perfect partner for photons and other cancer treatment modalities. Often there is a belief that the new technology ought to be better but many believe that they should be widely adopted in the clinic only after evidence has shown that they are at least as safe and efficacious as existing technologies, which are often less expensive. This is the case for proton radiotherapy. This session being both educational and debate will provide a good review of basics and technological advancement as well as a comprehensive clinical update for both proton and photon therapy. Future technology developments and how they will impact the potential dosimetric advantage of proton therapy will be discussed. Particularly the debate will focus on whether these developments will close or widen the gap between photon and proton therapy. Learning Objectives: To review challenges, limitations, and recent and future developments in proton therapy. To review challenges, limitations, recent and future developments in photon radiotherapy. To review current clinical trials and challenging clinical cases. C. Yu, No company or organization that my presentation mentions provided me with financial support. I am the Founder and CEO of Xcision Medical Systems, LLC. However, my presentation will not mention any product or technology developed by Xcision.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

TH-D-BRC-04: Panel Member

Interest in proton therapy has increased dramatically in the past couple of years, especially in the United States. There certainly is an important place for proton therapy in the arsenal of cancer treatments. Its dosimetric advantage and potential for low toxicity makes it the perfect partner for photons and other cancer treatment modalities. Often there is a belief that the new technology ought to be better but many believe that they should be widely adopted in the clinic only after evidence has shown that they are at least as safe and efficacious as existing technologies, which are often less expensive. This is the case for proton radiotherapy. This session being both educational and debate will provide a good review of basics and technological advancement as well as a comprehensive clinical update for both proton and photon therapy. Future technology developments and how they will impact the potential dosimetric advantage of proton therapy will be discussed. Particularly the debate will focus on whether these developments will close or widen the gap between photon and proton therapy. Learning Objectives: To review challenges, limitations, and recent and future developments in proton therapy. To review challenges, limitations, recent and future developments in photon radiotherapy. To review current clinical trials and challenging clinical cases. C. Yu, No company or organization that my presentation mentions provided me with financial support. I am the Founder and CEO of Xcision Medical Systems, LLC. However, my presentation will not mention any product or technology developed by Xcision.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2025

Thrifting iridium for hydrogen

Using renewable electricity to produce hydrogen fuel reduces reliance on fossil fuels. Proton exchange membrane water electrolyzers (PEMWEs) are the highest-performing commercialized technology. These devices split water into oxygen gas and hydrogen ions (protons) at the anode. The protons then migrate through an ion-conducting polymer membrane (ionomer) to be reduced to hydrogen gas at the cathode. Further, the anode reaction’s harsh environment requires the use of precious-metal catalysts, such as iridium oxide (IrO x ). Given the expense and scarcity, the design of electrodes that minimize the use of precious metals without compromising the requisite stability and activity is desired for large-scale hydrogen production. On page 791 of this issue, Shi et al. report that anchoring IrO x catalysts onto porous cerium-oxide (CeO x ) supports maintains performance even with much reduced precious metal use.

08 HYDROGEN↗

DOE OSTI2018

Preparation and Characterization of Nanoceramics for Solid Oxide Fuel Cells

Precursor powders in the ZrO{sub 2}–HfO{sub 2}–Y{sub 2}O{sub 3}–CeO{sub 2}, In{sub 2}O{sub 3}–ZrO{sub 2}, and NiO–Nd{sub 2}O{sub 3} systems for components of solid oxide fuel cells have been prepared by liquid-phase synthesis. We have determined formation conditions and the particle size of ZrO{sub 2-} and In{sub 2}O{sub 3-}based solid solutions and neodymium nickelate (Nd{sub 2}NiO{sub 4}), demonstrated the feasibility of producing nanocrystalline powders (10–30 nm) of tailored chemical composition in the temperature range 500–900°C, and optimized powder consolidation conditions. Nanoceramics with a crystallite size from 60 to 90 nm have been obtained and their microstructure and phase composition have been investigated. We have studied the electrical properties of the ZrO{sub 2-} and In{sub 2}O{sub 3-}based solid solutions and the Nd{sub 2}NiO{sub 4} compound and established the range of their electrical conductivity at temperatures from 300 to 1000°C: 2.27 × 10{sup –3} to 2.51 S/cm for the ZrO{sub 2}-based solid solution, 8.91 × 10{sup 1} to 6.59 × 10{sup 3} S/cm for the In{sub 2}O{sub 3}-based solid solution, and 3.98 × 10{sup 2} to 5.02 × 10{sup 2} S/cm for Nd{sub 2}NiO{sub 4}.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Sol–Gel Synthesis and Distinctive Structural Features of Ce{sub x}Zr{sub 1–x}O{sub 2} Solid Solutions

We have synthesized Ce{sub x}Zr{sub 1–x}O{sub 2} solid solutions via the thermal decomposition of xerogels of different compositions prepared by drying appropriate hydrosols. The synthesized materials have been characterized by thermal analysis, X-ray diffraction, and Raman spectroscopy. The results demonstrate that the solid solutions are formed at relatively low temperatures (450–600°C). The Ce{sub x}Zr{sub 1–x}O{sub 2} samples with x = 0.5–0.9 consist of a cubic solid solution. At a lower CeO{sub 2} content (x = 0.2), the material consists of a mixture of cubic and tetragonal phases.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Nanosized Particles of Tantalum, Hafnium, and Cerium Oxides Used with Monochromatic Photon Beams and Brachytherapy Sources

High-Z nanoparticles can increase the absorbed radiation dose if they are accumulated in tumor cells. The quantitative measure of this radiosensitization effect is the dose enhancement factor (DEF), that is, the ratio of the doses absorbed in the presence and in the absence of nanoparticles. In the present work, the values of the dose enhancement factors of Ta{sub 2}O{sub 5}, HfO{sub 2}, and CeO{sub 2} ceramic nanoparticles were calculated analytically for monochromatic radiation of the X-ray energy range (1–180 keV) and for low-energy sources for brachytherapy: {sup 103}Pd (mean energy, 20.6 keV), {sup 125}I (26.7 keV), and {sup 131}Cs (30.4 keV). For all types of nanoparticles in the concentration of 5 mg/mL, the values of the dose enhancement factor were high both for monochromatic radiation and for brachytherapy sources. The highest DEF values of ~1.7 were obtained for nanoparticles of tantalum oxide. For brachytherapy sources, the highest dose enhancement factors (1.48 to 1.67) were obtained for Ta{sub 2}O{sub 5} and HfO{sub 2} nanoparticles. These results confirm that ceramic nanoparticles are promising dose modifying agents for radiotherapy.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2021

Role of Pr-Vacancies and O-Interstitials on the Activity and Stability of (Pr 1−x Ln x ) 2 NiO 4 (Ln = La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) towards Oxygen Reduction Reactions: A DFT Study

Praseodymium nickelate, Pr 2 NiO 4 (PNO), is a promising electrode to promote oxygen reduction reaction (ORR) in a solid oxide fuel cell, but it exhibits phase transformation during electrochemical operation. The origin of the simultaneous phase transformation and high electrochemical performance remains obscure. We carried out a systematic density functional theory study to elucidate the mechanism for this conjugated phenomenon. Charge, electronic structure, and normal-mode analysis suggest the presence of peroxide. Our study shows that the formation of peroxide (O 2 2– ) is attributed to both oxygen interstitials and Pr vacancies. The peroxide species limits the oxygen ion migration due to the additional energy required to break its O–O bond, which leads to a decrease in ORR activity. Subsequently, we investigate the diffusion paths of Pr-ions while comparing them with those of other Ln 3+ ions (La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) in PNO. The formation energies for various Ln 3+ cation occupancies are calculated, as well as segregation energies in CeO 2 (111) surfaces. Lastly, criteria for effective Ln 3+ dopants are developed. La, Nd, and Pm are proposed as potential substituents in PNO to obtain a stable structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

Nanostructured Cathodes for Solid Oxide Fuel Cells by a Solution Spray-Coating Process

Composite nano-cathodes containing Sr-doped LaMnO 3 (LSM) and Gd 2 O 3 -doped CeO 2 (GDC) were deposited on yttria-stabilized zirconia (YSZ) discs and YSZ/NiO + YSZ bi-layer discs using an aqueous solution. The samples were heated over a range of temperatures from 700°C to 1200°C to form LSM + GDC porous films. The crystallite size was estimated using X-ray diffraction (XRD) Scherrer formula. The crystallite size was in the ~3 nm to ~80 nm range. Polarization resistance was measured by electrochemical impedance spectroscopy (EIS) from 400°C to 700°C. Nano-cathodes of ~70 nm thickness fired at 700°C exhibited polarization resistance of ~0.23 Ωcm 2 at 700°C. By contrast, LSM + YSZ cathodes made by a conventional process exhibited polarization resistance of ~2 Ωcm 2 . Fuel cell tests were conducted at 700°C on cells with nano-cathodes and conventional LSM + YSZ cathode. The maximum power density was ~0.51 Wcm –2 with nano-cathodes. By contrast, the corresponding power density with conventional LSM + YSZ cathodes was ~0.11 Wcm –2 . Here, the present work shows that very thin cathode functional layers can be deposited on sintered YSZ/NiO + YSZ bi-layer discs by using an aqueous solution. This approach in principle could be extended to large area cells.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Software-Defined Data Center Network Architecture using VXLAN-based BGP EVPN for Dynamic Workflows in a Supercomputing Environment (VXLAN-based BGP EVPN Fabric for HPC) v1

This software repository automates the deployment of a multi-vendor VXLAN-based BGP EVPN architecture, leveraging Containerlab to instantiate a stretched CLOS topology. It integrates Linux, Nokia SR Linux, and Arista cEOS, using BGP for underlay, overlay, and topology extension. The software enables rapid prototyping and testing of advanced network configurations. Its key advantage lies in providing a dynamic, programmable environment for research and development of critical technologies supporting dynamic workflows within supercomputing environments, surpassing the limitations of static, vendor-locked alternatives by fostering interoperability and agility.

Kumar, Ronal [Lawrence Berkeley National Laborator↗

DOE OSTI2024

Spectral Data Fusion From Handheld Laser-Induced Breakdown Spectroscopy (LIBS) and X-ray Fluorescence (XRF) Analyzers for Improved Detection of Cerium in a Simulated Dispersal Accident

Here, this work implements a mid-level data fusion methodology on spectral data from handheld X-ray fluorescence and laser-induced breakdown spectroscopy analyzers to quantify plutonium surrogate (CeO 2 ) contamination in soil samples for the first time. Spectral data from each analyzer were used independently to train supervised machine learning regressions to predict Ce concentration. Fused features from both data sets were then used to train the same models, comparing prediction performance by evaluating model precision and sensitivity. Fusing principal component scores from the two sensors yielded an order of magnitude improvement in precision and sensitivity of predictions made with an artificial neural network, compared to predictions made by models trained on independent sensor data. As a result, a boosted ensemble trained on the fused spectral features yielded an ideal predictor with root-mean-squared error on the order of 10 –6 and calculated limit of detection order 10 –5 wt %.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2021

Thin-film chemical expansion of ceria based solid solutions: laser vibrometry study

The chemical expansion of Pr 0.1 Ce 0.9 O 2-δ (PCO) and CeO 2-δ thin films is investigated in the temperature range between 600 °C and 800 °C by laser Doppler vibrometry (LDV). It enables non-contact determination of nanometer scale changes in film thickness at high temperatures. The present study is the first systematic and detailed investigation of chemical expansion of doped and undoped ceria thin films at temperatures above 650 °C. The thin films were deposited on yttria stabilized zirconia substrates (YSZ), operated as an electrochemical oxygen pump, to periodically adjust the oxygen activity in the films, leading to reversible expansion and contraction of the film. This further leads to stresses in the underlying YSZ substrates, accompanied by bending of the overall devices. Film thickness changes and sample bending are found to reach up to 10 and several hundred nanometers, respectively, at excitation frequencies from 0.1 to 10 Hz and applied voltages from 0–0.75 V for PCO and 0–1 V for ceria. At low frequencies, equilibrium conditions are approached. As a consequence maximum thin-film expansion of PCO is expected due to full reduction of the Pr ions. The lower detection limit for displacements is found to be in the subnanometer range. At 800 °C and an excitation frequency of 1 Hz, the LDV shows a remarkable resolution of 0.3 nm which allows, for example, the characterization of materials with small levels of expansion, such as undoped ceria at high oxygen partial pressure. As the correlation between film expansion and sample bending is obtained through this study, a dimensional change of a free body consisting of the same material can be calculated using the high resolution characteristics of this system. A minimum detectable dimensional change of 5 pm is estimated even under challenging high-temperature conditions at 800 °C opening up opportunities to investigate electro-chemo-mechanical phenomena heretofore impossible to investigate. The expansion data are correlated with previous results on the oxygen nonstoichiometry of PCO thin films, and a defect model for bulk ceria solid solutions is adopted to calculate the cation and anion radii changes in the constrained films during chemical expansion. The constrained films exhibit anisotropic volume expansion with displacements perpendicular to the substrate plane nearly double that of bulk samples. The PCO films used here generate high total displacements of several 100 nm’s with high reproducibility. Consequently, PCO films are identified to be a potential core component of high-temperature actuators. They benefit not only from high displacements at temperatures where most piezoelectric materials no longer operate while exhibiting, low voltage operation and low energy consumption.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2017

Molecular Dynamics Simulation of Fission Fragment Damage in Nuclear Fuel and Surrogate Material

We have performed classical molecular dynamics simulations of swift heavy ion damage, typical of fission fragments, in nuclear fuel (UO2) for energy deposition per unit length of 3.9 keV/nm. We did not observe amorphization. The damage mainly consisted of isolated point defects. Only about 1% of the displacements occur on the uranium sublattice. Oxygen Frenkel pairs are an order of magnitude more numerous than uranium Frenkel pairs in the primary damage state. In contrast, previous results show that the ratio of Frenkel pairs on the two sublattices is close to the stoichiometric ratio in ceria. These differences in the primary damage state may lead to differences in radiation response of UO2 and CeO2.

Molecular dynamics, radiation damage in materials,↗

DOE OSTI2020

Materials Data on Ce4Ga2S5O4 by Materials Project

(CeO)4Ga2S5 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Ce3+ sites. In the first Ce3+ site, Ce3+ is bonded in a 4-coordinate geometry to three S2- and four O2- atoms. There are two shorter (3.07 Å) and one longer (3.28 Å) Ce–S bond lengths. There are a spread of Ce–O bond distances ranging from 2.32–2.39 Å. In the second Ce3+ site, Ce3+ is bonded in a 4-coordinate geometry to four S2- and four O2- atoms. There are a spread of Ce–S bond distances ranging from 2.98–3.02 Å. There are a spread of Ce–O bond distances ranging from 2.30–2.36 Å. In the third Ce3+ site, Ce3+ is bonded in a 4-coordinate geometry to three S2- and four O2- atoms. There are two shorter (3.05 Å) and one longer (3.37 Å) Ce–S bond lengths. There are a spread of Ce–O bond distances ranging from 2.33–2.35 Å. In the fourth Ce3+ site, Ce3+ is bonded in a 4-coordinate geometry to four S2- and four O2- atoms. There are a spread of Ce–S bond distances ranging from 2.96–3.03 Å. There are a spread of Ce–O bond distances ranging from 2.33–2.38 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four S2- atoms to form corner-sharing GaS4 tetrahedra. There are a spread of Ga–S bond distances ranging from 2.25–2.35 Å. In the second Ga3+ site, Ga3+ is bonded in a distorted trigonal non-coplanar geometry to three S2- atoms. There are a spread of Ga–S bond distances ranging from 2.55–2.64 Å. There are five inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to four Ce3+ and one Ga3+ atom. In the second S2- site, S2- is bonded in a 1-coordinate geometry to two equivalent Ce3+ and one Ga3+ atom. In the third S2- site, S2- is bonded in a 1-coordinate geometry to two equivalent Ce3+ and one Ga3+ atom. In the fourth S2- site, S2- is bonded in a 1-coordinate geometry to four Ce3+ and one Ga3+ atom. In the fifth S2- site, S2- is bonded in a 5-coordinate geometry to two Ce3+ and three Ga3+ atoms. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four Ce3+ atoms to form a mixture of corner and edge-sharing OCe4 tetrahedra. In the second O2- site, O2- is bonded to four Ce3+ atoms to form a mixture of corner and edge-sharing OCe4 tetrahedra. In the third O2- site, O2- is bonded to four Ce3+ atoms to form a mixture of corner and edge-sharing OCe4 tetrahedra. In the fourth O2- site, O2- is bonded to four Ce3+ atoms to form a mixture of corner and edge-sharing OCe4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2014

SESAME 96170, a solid-liquid equation of state for CeO2

I describe an equation of state (EOS) for the low-pressure solid phase and liquid phase of cerium (IV) oxide, CeO 2 . The models and parameters used to calculate the EOS are presented in detail, and I compare with data for the full-density crystal. Hugoniot data are available only for high-porosity powders, and I discuss difficulties in comparing with such data. I have constructed SESAME 96170, an EOS for cerium (IV) oxide that includes the ambient solid and liquid phases. The EOS extends over the full standard SESAME range, but should not be used at low temperatures and high densities because of the lack of a high-pressure solid phase. I have described the models used to compute the three terms of the EOS (cold curve, nuclear, and thermal electronic), and I have given the parameters used in the models. They were determined by comparison with experimental data at P = 1 atm, including the constant-pressure specific heat, coefficient of thermal expansion, and melting and boiling points. The EOS compares well with data in its intended range of validity, but the presence of high-frequency optical modes in its phonon spectrum limits the agreement of our models with thermal data. The next step is to construct a multiphase EOS that includes the low- and high-pressure solid phases and the liquid. The DAC data from Duclos will most strongly constrain the parameters of the high-pressure solid. A remaining issue is the comparison of the crystal-density EOS with experimental Hugoniot data, which are taken at much lower initial data because the samples are porous powders. A satisfactory means of modeling porosity, allowing comparison of theory and experiment, has not yet been produced.

36 MATERIALS SCIENCE↗

DOE OSTI2014

SESAME 96171, a three-phase equation of state for CeO2

We describe an equation of state (EOS) for cerium (IV) oxide, CeO 2 , that includes two solid phases and the liquid. The models and parameters used to calculate the EOS are presented in detail, and we compare with data for both crystal phases and ambient melt. We discuss complications that arise when making multiphase EOS.

36 MATERIALS SCIENCE↗