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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Phase 2 Trial of De-intensified Chemoradiation Therapy for Favorable-Risk Human Papillomavirus–Associated Oropharyngeal Squamous Cell Carcinoma

Purpose: To perform a prospective, multi-institutional, phase 2 study of a substantial decrease in concurrent chemoradiation therapy (CRT) intensity as primary treatment for favorable-risk, human papillomavirus–associated oropharyngeal squamous cell carcinoma. Methods and Materials: The major inclusion criteria were: (1) T0 to T3, N0 to N2c, M0; (2) human papillomavirus or p16 positive; and (3) minimal/remote smoking history. Treatment was limited to 60 Gy intensity modulated radiation therapy with concurrent weekly intravenous cisplatinum (30 mg/m{sup 2}). The primary study endpoint was pathologic complete response (pCR) rate based on required biopsy of the primary site and dissection of pretreatment positive lymph node regions, regardless of radiographic response. Power computations were performed for the null hypothesis that the pCR rate is 87% and n=40, resulting in a type 1 error of 14.2%. Secondary endpoint measures included physician-reported toxicity (Common Toxicity Terminology for Adverse Events, CTCAE), patient-reported symptoms (PRO-CTCAE), and modified barium swallow studies. Results: The study population was 43 patients. The pCR rate was 86% (37 of 43). The incidence of CTCAE grade 3/4 toxicity and PRO-CTCAE severe/very severe symptoms was as follows: mucositis 34%/45%, general pain 5%/48%, nausea 18%/52%, vomiting 5%/34%, dysphagia 39%/55%, and xerostomia 2%/75%. Grade 3/4 hematologic toxicities were 11%. Thirty-nine percent of patients required a feeding tube for a median of 15 weeks (range, 5-22 weeks). There were no significant differences in modified barium swallow studies before and after CRT. Conclusions: The pCR rate with decreased intensity of therapy with 60 Gy of IMRT and weekly low-dose cisplatinum is very high in favorable-risk oropharyngeal squamous cell carcinoma, with evidence of decreased toxicity compared with standard therapies. (ClinicalTrials.gov) ID: (NCT01530997).

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Serum Transforming Growth Factor-β1 Change After Neoadjuvant Chemoradiation Therapy Is Associated With Postoperative Pulmonary Complications in Esophageal Cancer Patients Undergoing Combined Modality Therapy

Purpose: Our aim was to investigate the association of clinical factors, dosimetric parameters, and biomarkers with postoperative pulmonary complications (PPCs) in patients with locally advanced esophageal squamous cell carcinoma (ESCC) treated by neoadjuvant concurrent chemoradiation therapy (CCRT) under strict pulmonary dose constraints and esophagectomy. Methods and Materials: We prospectively enrolled 112 patients undergoing trimodality treatment (including radiation therapy [40 Gy], concurrent taxane-/5-fluorouracil-based regimens, and radical esophagectomy) for ESCC. A PPC was defined as pneumonia or acute respiratory distress syndrome within 30 days after surgery. Serum samples were collected before and within 1 month after CCRT. The association of serum biomarkers with PPCs was detected by proximity ligation assay (PLA) and verified by enzyme-linked immunosorbent assay. Associations of clinical factors, lung dosimetric parameters, and biomarkers with PPC were tested statistically. Results: Thirty-three patients (29.5%) had PPCs. None of the dosimetric parameters was associated with PPCs. Preoperative functional vital capacity (FVC) was significantly associated with PPCs (P=.004). Of the 15 PLA-screened biomarkers, posttreatment transforming growth factor-β1 (TGF-β1) was borderline significantly associated with PPCs (P=.087). Patients with PPCs had significantly larger pre-CCRT to post-CCRT decrease in serum TGF-β1 concentration (−11,310 vs −5332 pg/mL, P=.005) and higher pre-CCRT to post-CCRT percent decline in serum TGF-β1 concentration (−37.4% vs −25.0%, P=.009) than patients without PPCs. On multivariate analysis, preoperative FVC (P=.003) and decrease in TGF-β1 >7040 pg/mL (P=.014) were independent factors associated with PPCs. Conclusions: Preoperative FVC and decrease in serum TGF-β1 level after dose-limited CCRT to the lung are associated with the development of PPCs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Thoracic Vertebral Body Irradiation Contributes to Acute Hematologic Toxicity During Chemoradiation Therapy for Non-Small Cell Lung Cancer

Purpose: To determine the relationships between radiation doses to the thoracic bone marrow and declines in blood cell counts in non-small cell lung cancer (NSCLC) patients treated with chemoradiation therapy (CRT). Methods and Materials: We included 52 patients with NSCLC treated with definitive concurrent carboplatin–paclitaxel and RT. Dose-volume histogram (DVH) parameters for the thoracic vertebrae (TV), sternum, scapulae, clavicles, and ribs were assessed for associations with changes in blood counts during the course of CRT. Linear and logistic regression analyses were performed to identify associations between hematologic nadirs and DVH parameters. A DVH parameter of Vx was the percentage of the total organ volume exceeding x radiation dose. Results: Grade ≥3 hematologic toxicity including neutropenia developed in 21% (n=11), leukopenia in 42% (n=22), anemia in 6% (n=3), and throbocytopenia in 2% (n=1) of patients. Greater RT dose to the TV was associated with higher risk of grade ≥3 leukopenia across multiple DVH parameters, including TV V{sub 20} (TVV) (odds ratio [OR] 1.06; P=.025), TVV{sub 30} (OR 1.07; P=.013), and mean vertebral dose (MVD) (OR 1.13; P=.026). On multiple regression analysis, TVV{sub 30} (β = −0.004; P=.018) and TVV{sub 20} (β = −0.003; P=.048) were associated with white blood cell nadir. Additional bone marrow sites (scapulae, clavicles, and ribs) did not affect hematologic toxicity. A 20% chance of grade ≥3 leukopenia was associated with a MVD of 13.5 Gy and a TTV{sub 30} of 28%. Cutoff values to avoid grade ≥3 leukopenia were MVD ≤23.9 Gy, TVV{sub 20} ≤56.0%, and TVV{sub 30} ≤52.1%. Conclusions: Hematologic toxicity is associated with greater RT doses to the TV during CRT for NSCLC. Sparing of the TV using advanced radiation techniques may improve tolerance of CRT and result in improved tolerance of concurrent chemotherapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Gemcitabine Plus Radiation Therapy for High-Grade Glioma: Long-Term Results of a Phase 1 Dose-Escalation Study

Purpose: To evaluate the tolerability and efficacy of gemcitabine plus radiation therapy (RT) in this phase 1 study of patients with newly diagnosed malignant glioma (HGG). Patients and Methods: Between 2004 and 2012, 29 adults with HGG were enrolled. After any extent of resection, RT (60 Gy over 6 weeks) was given concurrent with escalating doses of weekly gemcitabine. Using a time-to-event continual reassessment method, 5 dose levels were evaluated starting at 500 mg/m{sup 2} during the last 2 weeks of RT and advanced stepwise into earlier weeks. The primary objective was to determine the recommended phase 2 dose of gemcitabine plus RT. Secondary objectives included progression-free survival, overall survival (OS), and long-term toxicity. Results: Median follow-up was 38.1 months (range, 8.9-117.5 months); 24 patients were evaluable for toxicity. After 2005 when standard practice changed, patients with World Health Organization grade 4 tumors were no longer enrolled. Median progression-free survival for 22 patients with grade 3 tumors was 26.0 months (95% confidence interval [CI] 15.6-inestimable), and OS was 48.5 months (95% CI 26.8-inestimable). In 4 IDH mutated, 1p/19q codeleted patients, no failures occurred, with all but 1 alive at time of last follow-up. Seven with IDH mutated, non-codeleted tumors with ATRX loss had intermediate OS of 73.5 months (95% CI 32.8-inestimable). Six nonmutated, non-codeleted patients had a median OS of 26.5 months (95% CI 25.4-inestimable). The recommended phase 2 dose of gemcitabine plus RT was 750 mg/m{sup 2}/wk given the last 4 weeks of RT. Dose reductions were most commonly due to grade 3 neutropenia; no grade 4 or 5 toxicities were seen. Conclusions: Gemcitabine concurrent with RT is well-tolerated and yields promising outcomes, including in patients with adverse molecular features. It is a candidate for further study, particularly for poor-prognosis patient subgroups with HGG.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Reirradiation of Head and Neck Cancers With Intensity Modulated Radiation Therapy: Outcomes and Analyses

Purpose: To review our 15-year institutional experience using intensity modulated radiation therapy (IMRT) to reirradiate patients with head and neck squamous cell carcinomas (HNSCC) and identify predictors of outcomes and toxicity. Methods and Materials: We retrospectively reviewed the records of 227 patients who received head and neck reirradiation using IMRT from 1999 to 2014. Patients treated with noncurative intent were excluded. Radiation-related acute and late toxicities were recorded. Prognostic variables included performance status, disease site, disease-free interval, chemotherapy, and RT dose and volume. Correlative analyses were performed separately for surgery and nonsurgery patients. Results: Two hundred six patients (91%) were retreated with curative intent, and 173 had HNSCC histology; 104 (50%) underwent salvage resection, and 135 (66%) received chemotherapy. Median follow-up after reirradiation was 24.7 months. Clinical outcomes were worse for HNSCC patients, with 5-year locoregional control, progression-free survival, and overall survival rates of 53%, 22%, and 32%, respectively, compared with 74%, 59%, and 79%, respectively, for non-HNSCC patients. On multivariate analysis, concurrent chemotherapy and retreatment site were associated with tumor control, whereas performance status was associated with survival. Favorable prognostic factors specific to surgery patients were neck retreatment and lack of extracapsular extension, whereas for nonsurgery patients, these were a nasopharynx subsite and complete response to induction chemotherapy. Actuarial rates of grade ≥3 toxicity were 32% at 2 years and 48% at 5 years, with dysphagia or odynophagia being most common. Increased grade ≥3 toxicity was associated with retreatment volume >50 cm{sup 3} and concurrent chemotherapy. Conclusions: Reirradiation with IMRT either definitively or after salvage surgery can produce promising local control and survival in selected patients with head and neck cancers. Treatment-related toxicity remains significant. Prognostic factors are emerging to guide multidisciplinary treatment approaches and clinical trial design.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Dose and Fractionation in Radiation Therapy of Curative Intent for Non-Small Cell Lung Cancer: Meta-Analysis of Randomized Trials

Purpose: The optimum dose and fractionation in radiation therapy of curative intent for non-small cell lung cancer remains uncertain. We undertook a published data meta-analysis of randomized trials to examine whether radiation therapy regimens with higher time-corrected biologically equivalent doses resulted in longer survival, either when given alone or when given with chemotherapy. Methods and Materials: Eligible studies were randomized comparisons of 2 or more radiation therapy regimens, with other treatments identical. Median survival ratios were calculated for each comparison and pooled. Results: 3795 patients in 25 randomized comparisons of radiation therapy dose were studied. The median survival ratio, higher versus lower corrected dose, was 1.13 (95% confidence interval [CI] 1.04-1.22) when radiation therapy was given alone and 0.83 (95% CI 0.71-0.97) when it was given with concurrent chemotherapy (P for difference=.001). In comparisons of radiation therapy given alone, the survival benefit increased with increasing dose difference between randomized treatment arms (P for trend=.004). The benefit increased with increasing dose in the lower-dose arm (P for trend=.01) without reaching a level beyond which no further survival benefit was achieved. The survival benefit did not differ significantly between randomized comparisons where the higher-dose arm was hyperfractionated and those where it was not. There was heterogeneity in the median survival ratio by geographic region (P<.001), average age at randomization (P<.001), and year trial started (P for trend=.004), but not for proportion of patients with squamous cell carcinoma (P=.2). Conclusions: In trials with concurrent chemotherapy, higher radiation therapy doses resulted in poorer survival, possibly caused, at least in part, by high levels of toxicity. Where radiation therapy was given without chemotherapy, progressively higher radiation therapy doses resulted in progressively longer survival, and no upper dose level was found above which there was no further benefit. These findings support the consideration of further radiation therapy dose escalation trials, making use of modern treatment methods to reduce toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

{sup 18}F-Fluorodeoxyglucose/Positron Emission Tomography Predicts Patterns of Failure After Definitive Chemoradiation Therapy for Locally Advanced Non-Small Cell Lung Cancer

Background: We previously reported that pretreatment positron emission tomography (PET) identifies lesions at high risk for progression after concurrent chemoradiation therapy (CRT) for locally advanced non-small cell lung cancer (NSCLC). Here we validate those findings and generate tumor control probability (TCP) models. Methods: We identified patients treated with definitive, concurrent CRT for locally advanced NSCLC who underwent staging {sup 18}F-fluorodeoxyglucose/PET/computed tomography. Visible hypermetabolic lesions (primary tumors and lymph nodes) were delineated on each patient's pretreatment PET scan. Posttreatment imaging was reviewed to identify locations of disease progression. Competing risks analyses were performed to examine metabolic tumor volume (MTV) and radiation therapy dose as predictors of local disease progression. TCP modeling was performed to describe the likelihood of local disease control as a function of lesion size. Results: Eighty-nine patients with 259 hypermetabolic lesions (83 primary tumors and 176 regional lymph nodes) met the inclusion criteria. Twenty-eight patients were included in our previous report, and the remaining 61 constituted our validation cohort. The median follow-up time was 22.7 months for living patients. In 20 patients, the first site of progression was a primary tumor or lymph node treated with radiation therapy. The median time to progression for those patients was 11.5 months. Data from our validation cohort confirmed that lesion MTV predicts local progression, with a 30-month cumulative incidence rate of 23% for lesions above 25 cc compared with 4% for lesions below 25 cc (P=.008). We found no evidence that radiation therapy dose was associated with local progression risk. TCP modeling yielded predicted 30-month local control rates of 98% for a 1-cc lesion, 94% for a 10-cc lesion, and 74% for a 50-cc lesion. Conclusion: Pretreatment FDG-PET identifies lesions at risk for progression after CRT for locally advanced NSCLC. Strategies to improve local control should be tested on high-risk lesions, and treatment deintensification for low-risk lesions should be explored.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Multicenter Study of Carbon-Ion Radiation Therapy for Mucosal Melanoma of the Head and Neck: Subanalysis of the Japan Carbon-Ion Radiation Oncology Study Group (J-CROS) Study (1402 HN)

Purpose: To evaluate the efficacy and safety of carbon-ion radiation therapy (RT) for mucosal melanoma of the head and neck (MMHN) in the Japan Carbon-Ion Radiation Oncology Study Group study. Methods and Materials: Patients with MMHN with N0-1M0 status who were treated with carbon-ion RT at 4 institutions in Japan between November 2003 and December 2014 were analyzed retrospectively. Two hundred sixty patients (male, 111; female, 149; median age, 68 years) with histologically proven MMHN were enrolled. Results: Primary sites included the nasal cavity in 178 patients, paranasal sinuses in 43, oral cavity in 27, and pharynx in 12. Eighty-six patients had T3 tumors, 147 had T4a tumors, and 27 had T4b tumors. Two hundred fifty-one patients were diagnosed with N0 disease, and 9 with N1 disease. The median total dose and number of fractions were 57.6 Gy RBE (relative biological effectiveness) and 16, respectively. Chemotherapy including dimethyl traizeno imidazole carboxamide was used concurrently in 129 patients. The median follow-up duration was 22 months (range, 1-132 months). The 2-year overall survival and local control rates were 69.4% and 83.9%, respectively. Multivariate analysis showed that gross tumor volume and concurrent chemotherapy were significant prognostic factors for overall survival. Grade 3 and grade 4 late morbidities were observed in 27 and 7 patients (5 developed ipsilateral blindness, 1 mucosal ulcer, and 1 second malignant disease in the irradiated volume), respectively. No patients developed grade 5 late morbidities. Conclusion: Carbon-ion RT is a promising treatment option for MMHN.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Prospective Study of Hippocampal-Sparing Prophylactic Cranial Irradiation in Limited-Stage Small Cell Lung Cancer

Purpose: To prospectively evaluate cognitive function and intracranial failure patterns after hippocampal-sparing prophylactic cranial irradiation (PCI) for limited-stage small cell lung cancer (SCLC). Methods and Materials: Adults with limited-stage SCLC, achieving a complete response to chemoradiotherapy and no brain metastases, were eligible. Patients received PCI 25 Gy/10 fractions, with a mean hippocampal dose limited to <8 Gy and ≥90% of the brain receiving 90% of the prescription. A diverse battery of neuropsychological testing was performed at baseline and 6 and 12 months after PCI. Brain MRI scans were performed at baseline and 6, 12, 18, and 24 months. The primary endpoint was memory measured by the Hopkins Verbal Learning Test-Revised Delayed Recall at 6 months after PCI. The 25-Gy arm of Radiation Therapy Oncology Group protocol 0212 was used as a reference of potential efficacy. Development of intracranial metastases was recorded. Overall survival and progression-free survival were estimated using the Kaplan-Meier method. Results: Eight men and 12 women with a median age of 61 years enrolled. Two-year overall survival was 88% (95% confidence interval 68%-100%). There was no significant decline in performance between baseline and 6 or 12 months for any of the tests. The association between baseline intelligence quotient and change in performance on testing was not significant. Magnetic resonance imaging revealed asymptomatic brain metastases at a cumulative rate of 20%, with no concurrent extracranial progression. Two patients developed a metastasis in the under-dosed region. Neither involved the dentate gyrus, but 1 involved the avoidance region. Both patients concurrently developed additional metastasis in fully treated brain regions. There were 2 neurologic deaths. Conclusions: This prospective study suggests a potential benefit of hippocampal sparing in limiting the neuropsychological sequelae of brain radiation, but with a risk of failures in the spared region. These data strongly support continued enrollment on ongoing cooperative group randomized trials. Clinical Trials registration number: (NCT01797159).

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Exercise Therapy and Radiation Therapy for Cancer: A Systematic Review

Exercise therapy (ET) is shown to improve toxicity and surrogates of survival for patients receiving chemotherapy. Current National Comprehensive Cancer Network (NCCN) guidelines lack recommendations for concurrent radiation therapy (RT) and ET. The main objective was to determine the impact of concurrent ET + RT with respect to (1) acceptability, feasibility, safety; and (2) to demonstrate how incorporating ET in cancer treatment can enhance patient-reported outcomes (PROs) and physical function—defined as strength or exercise capacity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Electrical and seismic response of saline permafrost soil during freeze - Thaw transition

We conducted laboratory studies on the geophysical signals from Arctic saline permafrost soils to help understand the physical and mechanical processes during freeze-thaw cycles. Our results revealed low electrical resistivity (< 20 Ωm) and elastic moduli (7.7 GPa for Young's modulus and 2.9 GPa for shear modulus) at temperatures down to ~- 10 °C, indicating the presence of a significant amount of unfrozen saline water under the current field conditions. The spectral induced polarization signal showed a systematic shift during the freezing process, affected by concurrent changes of temperature, salinity, and ice formation. An anomalous induced polarization response was first observed during the transient period of supercooling and the onset of ice nucleation. Seismic measurements showed a characteristic maximal attenuation at the temperatures immediately below the freezing point, followed by a decrease with decreasing temperature. The calculated elastic moduli showed a non-hysteric response during the freeze – thaw cycle, which was different from the concurrently measured electrical resistivity response where a differential resistivity signal is observed depending on whether the soil is experiencing freezing or thawing. The differential electrical resistivity signal presents challenges for unfrozen water content estimation based on Archie's law. Using an improved formulation of Archie's law with a variable cementation exponent, the unfrozen water content estimation showed a large variation depending on the choice of the resistivity data during either a freezing or thawing cycle. Combining the electrical and seismic results, we suggest that, rather than a large hysteresis in the actual unfrozen water content, the shift of the resistivity response may reflect the changes of the distribution pattern of the unfrozen water (or ice) in the soil matrix during repeated freeze and thaw processes. Collectively, our results provide an improved petrophysical understanding of the physical and mechanical properties of saline permafrost during freeze – thaw transitions, and suggest that large uncertainty may exist when estimating the unfrozen water content using electrical resistivity data.

58 GEOSCIENCES↗
DOE OSTI2015

A projected preconditioned conjugate gradient algorithm for computing many extreme eigenpairs of a Hermitian matrix

We present an iterative algorithm for computing an invariant subspace associated with the algebraically smallest eigenvalues of a large sparse or structured Hermitian matrix A. We are interested in the case in which the dimension of the invariant subspace is large (e.g., over several hundreds or thousands) even though it may still be small relative to the dimension of A. These problems arise from, for example, density functional theory (DFT) based electronic structure calculations for complex materials. The key feature of our algorithm is that it performs fewer Rayleigh–Ritz calculations compared to existing algorithms such as the locally optimal block preconditioned conjugate gradient or the Davidson algorithm. It is a block algorithm, and hence can take advantage of efficient BLAS3 operations and be implemented with multiple levels of concurrency. We discuss a number of practical issues that must be addressed in order to implement the algorithm efficiently on a high performance computer.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Radiation response of alloy T91 at damage levels up to 1000 peak dpa

Ferritic/martensitic alloys are required for advanced reactor components to survive 500e600 neutroninduced dpa. Ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500e600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damage level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. In comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2019

Parallel streaming between heterogeneous HPC resources for real-time analysis

Performing analysis or generating visualizations concurrently with high performance simulations can yield great benefits compared to post-processing data. Writing and reading large volumes of data can be reduced or eliminated, thereby producing an I/O cost savings. One such method for concurrent simulation and analysis is in transit - streaming data from the resource running the simulation to a separate resource running the analysis. In transit analysis can be beneficial since computational resources may not have certain resources needed for visualization and analysis (e.g. GPUs) and to reduce the impact of performing analysis tasks to the run time of the simulation. When sending and receiving data in transit, data redistribution mechanisms are needed in order to support heterogeneous data layouts that may be required by the simulation and analysis applications. The work described in this paper compares two mechanisms for on-the-fly data redistribution when streaming data in parallel between two distributed memory applications. Finally, our results show that it is often more advantageous to stream data in the same layout as the sender and redistribute data amongst processes on the receiving end than to stream data in the final layout needed by the receiver.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

Application configuration selection for energy-efficient execution on multicore systems

Balanced performance and energy consumption are incorporated in the design of modern computer systems. Several runtime factors, such as concurrency levels, thread mapping strategies, and dynamic voltage and frequency scaling (DVFS) should be considered in order to achieve optimal energy efficiency fora workload. Selecting appropriate run-time factors, however, is one of the most challenging tasks because the run-time factors are architecture-specific and workload-specific. And while most existing works concentrate on either static analysis of the workload or run-time prediction results, we present a hybrid two-step method that utilizes concurrency levels and DVFS settings to achieve the energy efficiency configuration for a worldoad. The experimental results based on a Xeon E5620 server with NPB and PARSEC benchmark suites show that the model is able to predict the energy efficient configuration accurately. On average, an additional 10% EDP (Energy Delay Product) saving is obtained by using run-time DVFS for the entire system. An off-line optimal solution is used to compare with the proposed scheme. Finally, the experimental results show that the average extra EDP saved by the optimal solution is within 5% on selective parallel benchmarks.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Oxygen-storage behavior and local structure in Ti-substituted YMnO{sub 3}

Hexagonal manganates RMnO{sub 3} (R=Y, Ho, Dy) have been recently shown to exhibit oxygen-storage capacities promising for three-way catalysts, air-separation, and related technologies. Here, we demonstrate that Ti substitution for Mn can be used to chemically tune the oxygen-breathing properties of these materials towards practical applications. Specifically, Y(Mn{sub 1−x}Ti{sub x})O{sub 3} solid solutions exhibit facile oxygen absorption/desorption via reversible Ti{sup 3+}↔Ti{sup 4+} and Mn{sup 3+}↔Mn{sup 4+} reactions already in ambient air at ≈400 °C and ≈250 °C, respectively. On cooling, the oxidation of both cations is accompanied by oxygen uptake yielding a formula YMn{sup 3+}{sub 1−x-y}Mn{sup 4+}{sub y}Ti{sup 4+}{sub x}O{sub 3+δ}. The presence of Ti promotes the oxidation of Mn{sup 3+} to Mn{sup 4+}, which is almost negligible for YMnO{sub 3} in air, thereby increasing the uptake of oxygen beyond that required for a given Ti{sup 4+} concentration. The reversibility of the redox reactions is limited by sluggish kinetics; however, the oxidation process continues, if slowly, even at room temperature. The extra oxygen atoms are accommodated by the large interstices within a triangular lattice formed by the [MnO{sub 5}] trigonal bipyramids. According to bond distances from Rietveld refinements using the neutron diffraction data, the YMnO{sub 3} structure features under-bonded Mn and even more severely under-bonded oxygen atoms that form the trigonal bases of the [MnO{sub 5}] bipyramids. The tensile bond strain around the 5-fold coordinated Mn site and the strong preference of Ti{sup 4+}(and Mn{sup 4+}) for higher coordination numbers likely provide driving forces for the oxidation reaction. Reverse Monte Carlo refinements of the local atomic displacements using neutron total scattering revealed how the excess oxygen atoms are accommodated in the structure by correlated local displacements of the host atoms. Large displacements of the under-bonded host oxygen atoms play a key part in this lattice-relaxation process, facilitating reversible exchange of significant amounts of oxygen with atmosphere. - Graphical abstract: Concurrent redox reactions involving Ti and Mn yield facile absorption/desorption of excess oxygen. - Highlights: • Concurrent redox reactions involving Ti and Mn yield oxygen absorption/desorption. • Excess oxygen is accommodated as interstitials via correlated atomic shifts. • Oxygen breathing is facilitated by the under-bonding of host Mn and O atoms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

A comparative study of the transformation kinetics of recrystallization texture of CC and DC 3003 aluminum alloys

Highlights: • Recrystallization texture evolution in CC and DC 3003 aluminum alloys was investigated. • A huge difference in recrystallization texture exists between CC and DC AA 3003 alloys. • Concurrent precipitation enhanced the recrystallization activation energy of CC AA 3003 alloy. - Abstract: The evolution of recrystallization texture in cold-rolled CC and DC AA 3003 aluminum alloys was investigated by X-ray diffraction. The results show that a significant difference in recrystallization texture exists between the CC and DC AA 3003 alloys due to the effect of concurrent precipitation. For the CC AA 3003 alloy, low-temperature annealing of cold-rolled sheets results in very strong M and P recrystallization textures. The strength of the M and P recrystallization textures decrease significantly with increasing annealing temperature. For the DC AA 3003 alloy, the recrystallization texture consists of a major cube component and two minor R and Goss components after annealing at low temperatures. The cube, R and Goss recrystallization textures weaken with increasing annealing temperature. The transformation kinetics of recrystallization texture during isothermal annealing can be well described by the JMAK equation. For the CC AA 3003 alloy the n value decreases from about 2.9 to about 0.8 as the annealing temperature increases from 371 °C to 427 °C, while the n value is around 1.5 for the DC AA 3003 alloy. The apparent activation energy for recrystallization of the cold-rolled CC AA 3003 alloy is significantly higher than that of the cold-rolled DC AA 3003 alloy.

36 MATERIALS SCIENCE↗