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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 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Competing Risk Analysis of Neurologic versus Nonneurologic Death in Patients Undergoing Radiosurgical Salvage After Whole-Brain Radiation Therapy Failure: Who Actually Dies of Their Brain Metastases?

Purpose: To estimate the hazard for neurologic (central nervous system, CNS) and nonneurologic (non-CNS) death associated with patient, treatment, and systemic disease status in patients receiving stereotactic radiosurgery after whole-brain radiation therapy (WBRT) failure, using a competing risk model. Patients and Methods: Of 757 patients, 293 experienced recurrence or new metastasis following WBRT. Univariate Cox proportional hazards regression identified covariates for consideration in the multivariate model. Competing risks multivariable regression was performed to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) for both CNS and non-CNS death after adjusting for patient, disease, and treatment factors. The resultant model was converted into an online calculator for ease of clinical use. Results: The cumulative incidence of CNS and non-CNS death at 6 and 12 months was 20.6% and 21.6%, and 34.4% and 35%, respectively. Patients with melanoma histology (relative to breast) (aHR 2.7, 95% CI 1.5-5.0), brainstem location (aHR 2.1, 95% CI 1.3-3.5), and number of metastases (aHR 1.09, 95% CI 1.04-1.2) had increased aHR for CNS death. Progressive systemic disease (aHR 0.55, 95% CI 0.4-0.8) and increasing lowest margin dose (aHR 0.97, 95% CI 0.9-0.99) were protective against CNS death. Patients with lung histology (aHR 1.3, 95% CI 1.1-1.9) and progressive systemic disease (aHR 2.14, 95% CI 1.5-3.0) had increased aHR for non-CNS death. Conclusion: Our nomogram provides individual estimates of neurologic death after salvage stereotactic radiosurgery for patients who have failed prior WBRT, based on histology, neuroanatomical location, age, lowest margin dose, and number of metastases after adjusting for their competing risk of death from other causes.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Predictors of Locoregional Failure and Impact on Overall Survival in Patients With Resected Exocrine Pancreatic Cancer

Purpose: Resection of exocrine pancreatic cancer is necessary for cure, but locoregional and distant relapse is common. We evaluated our institutional experience to better understand risk factors for locoregional failure (LRF) and its impact on overall survival (OS). Methods and Materials: We reviewed 1051 consecutive patients with nonmetastatic exocrine pancreatic cancer who underwent resection at our institution between March 1987 and January 2011. Among them, 458 had adequate follow-up and evaluation for study inclusion. All patients received adjuvant chemotherapy (n=80 [17.5%]) or chemoradiation therapy (n=378 [82.5%]). Chemotherapy and chemoradiation therapy most frequently consisted of 6 cycles of gemcitabine and 50.4 Gy in 28 fractions with concurrent 5-fluorouracil, respectively. Locoregional control (LRC) and OS were estimated with the Kaplan-Meier method. Univariate and multivariate analyses were performed with Cox proportional hazards regression models incorporating propensity score. Results: Median patient age was 64.5 years (range: 29-88 years). Median follow-up for living patients was 84 months (range: 6-300 months). Extent of resection was R0 (83.8%) or R1 (16.2%). Overall crude incidence of LRF was 17% (n=79). The 5-year LRC for patients with and without radiation therapy was 80% and 68%, respectively (P=.003; hazard ratio [HR]: 0.45; 95% confidence interval [CI]: 0.28-0.76). Multivariate analysis, incorporating propensity score, indicated radiation therapy (P<.0001; HR: 0.23; 95% CI: 0.12-0.42) and positive lymph node ratio of ≥0.2 (P=.02; HR: 1.78; 95% CI: 1.10-2.9) were associated with LRC. In addition, LRF was associated with worse OS (P<.0001; HR: 5.0; 95% CI: 3.9-6.3). Conclusions: In our analysis of 458 patients with resected pancreatic cancer, positive lymph node ratio of ≥0.2 and no adjuvant chemoradiation therapy were associated with increased LRF risk. LRF was associated with poor OS. Radiation therapy should be considered as adjuvant locoregional treatment following pancreatic cancer resection.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Validating a Local Failure Risk Stratification for Use in Prospective Studies of Adjuvant Radiation Therapy for Bladder Cancer

Purpose: To inform prospective trials of adjuvant radiation therapy (adj-RT) for bladder cancer after radical cystectomy, a locoregional failure (LF) risk stratification was proposed. This stratification was developed and validated using surgical databases that may not reflect the outcomes expected in prospective trials. Our purpose was to assess sources of bias that may affect the stratification model's validity or alter the LF risk estimates for each subgroup: time bias due to evolving surgical techniques; trial accrual bias due to inclusion of patients who would be ineligible for adj-RT trials because of early disease progression, death, or loss to follow-up shortly after cystectomy; bias due to different statistical methods to estimate LF; and subgrouping bias due to different definitions of the LF subgroups. Methods and Materials: The LF risk stratification was developed using a single-institution cohort (n=442, 1990-2008) and the multi-institutional SWOG 8710 cohort (n=264, 1987-1998) treated with radical cystectomy with or without chemotherapy. We evaluated the sensitivity of the stratification to sources of bias using Fine-Gray regression and Kaplan-Meier analyses. Results: Year of radical cystectomy was not associated with LF risk on univariate or multivariate analysis after controlling for risk group. By use of more stringent inclusion criteria, 26 SWOG patients (10%) and 60 patients from the single-institution cohort (14%) were excluded. Analysis of the remaining patients confirmed 3 subgroups with significantly different LF risks with 3-year rates of 7%, 17%, and 36%, respectively (P<.01), nearly identical to the rates without correcting for trial accrual bias. Kaplan-Meier techniques estimated higher subgroup LF rates than competing risk analysis. The subgroup definitions used in the NRG-GU001 adj-RT trial were validated. Conclusions: These sources of bias did not invalidate the LF risk stratification or substantially change the model's LF estimates.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Patterns and Timing of Failure for Diffuse Large B-Cell Lymphoma After Initial Therapy in a Cohort Who Underwent Autologous Bone Marrow Transplantation for Relapse

Purpose: To evaluate the location and timing of initial recurrence in patients with diffuse large B-cell lymphoma (DLBCL) who subsequently underwent high-dose chemotherapy with autologous stem cell transplant (HDC/ASCT), to direct approaches for disease surveillance, elucidate the patterns of failure of contemporary treatment strategies, and guide adjuvant treatment decisions. Methods and Materials: We analyzed consecutive patients with DLBCL who underwent HDC/ASCT between May 1992 and March 2014 at our institution. Of the 187 evaluable patients, 8 had incomplete data, and 79 underwent HDC/ASCT as a component of initial treatment for de novo or refractory DLBCL and were excluded from further analysis. Results: The median age was 50.8 years; the median time to relapse was 1.3 years. Patients were segregated according to the initial stage at diagnosis, with early stage (ES) defined as stage I/II and advanced stage (AS) defined as stage III/IV. In total, 40.4% of the ES and 75.5% of the AS patients relapsed in sites of initial disease; 68.4% of those with ES disease and 75.0% of those with AS disease relapsed in sites of initial disease only. Extranodal relapses were common (44.7% in ES and 35.9% in AS) and occurred in a variety of organs, although gastrointestinal tract/liver (n=12) was most frequent. Conclusions: Most patients with DLBCL who relapse and subsequently undergo HDC/ASCT initially recur in the previously involved disease site(s). Time to recurrence is brief, suggesting that frequency of screening is most justifiably greatest in the early posttherapy years. © 2016 Elsevier Inc.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Reirradiation of Prostate Cancer Local Failures After Previous Curative Radiation Therapy: Long-Term Outcome and Tolerance

Purpose: To evaluate the safety, feasibility, side-effect profile, and proof of concept of external beam radiation therapy (EBRT) with or without a brachytherapy (BT) boost for salvage of exclusive local failure after primary EBRT for prostate cancer. Methods and Materials: Fourteen patients with presumed exclusive local recurrence after primary EBRT with or without BT were considered eligible for reirradiation. The median normalized total dose in 2-Gy fractions (NTD{sub 2Gy}, α/β ratio = 1.5 Gy) was 74 Gy (range, 66-98.4 Gy) at first irradiation. Median time between the first irradiation and the reirradiation was 6.1 years (range, 4.7-10.2 years). Results: Between 2003 and 2008 salvage treatment was delivered with a median NTD{sub 2Gy} of 85.1 Gy (range, 70-93.4) to the prostate with EBRT with (n=10) or without (n=4) BT. Androgen deprivation was given to 12 patients (median time of 12 months). No grade ≥3 toxicity was observed during and within 6 weeks after RT. After a median follow-up of 94 months (range, 48-172 months) after salvage RT, 5-year grade ≥3 genitourinary and gastrointestinal toxicity-free survival figures were 77.9% ± 11.3% and 57.1% ± 13.2%, respectively. Four patients presented with combined grade 4 genitourinary/gastrointestinal toxicity. The 5-year biochemical relapse-free, local relapse-free, distant metastasis-free, and cancer-specific survival rates were 35.7% ± 12.8%, 50.0% ± 13.4%, 85.7% ± 9.4%, and 100%, respectively. Conclusion: Salvage whole-gland reirradiation for patients with a suspicion of exclusive local recurrence after initial RT may be associated with a high rate of severe radiation-induced side effects and poor long-term biochemical and local control.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Brain Metastasis Velocity: A Novel Prognostic Metric Predictive of Overall Survival and Freedom From Whole-Brain Radiation Therapy After Distant Brain Failure Following Upfront Radiosurgery Alone

Purpose: Prior statistical models attempted to identify risk factors for time to distant brain failure (DBF) or time to salvage whole-brain radiation therapy (WBRT) to predict the benefit of early WBRT versus stereotactic radiosurgery (SRS) alone. We introduce a novel clinical metric, brain metastasis velocity (BMV), for predicting clinical outcomes after initial DBF following upfront SRS alone. Methods and Materials: BMV was defined as the cumulative number of new brain metastases that developed over time since first SRS in years. Patients were classified by BMV into low-, intermediate-, and high-risk groups, consisting of <4, 4 to 13, and >13 new metastases per year, respectively. Histology, number of metastases at the time of first SRS, and systemic disease status were assessed for effect on BMV. Results: Of 737 patients treated at our institution with upfront SRS without WBRT, 286 had ≥1 DBF event. A lower BMV predicted for improved overall survival (OS) following initial DBF (log-rank P<.0001). Median OS for the low, intermediate, and high BMV groups was 12.4 months (95% confidence interval [CI], 10.4-16.9 months), 8.2 months (95% CI, 5.0-9.7 months), and 4.3 months (95% CI, 2.6-6.7 months), respectively. Multivariate analysis showed that BMV remained the dominant predictor of OS, with a hazard ratio of 2.75 for the high BMV group (95% CI, 1.94-3.89; P<.0001) and a hazard ratio of 1.65 for the intermediate BMV group (95% CI, 1.18-2.30; P<.004). A lower BMV was associated with decreased rates of salvage WBRT (P=.02) and neurologic death (P=.008). Factors predictive for a higher BMV included ≥2 initial brain metastases (P=.004) and melanoma histology (P=.008). Conclusions: BMV is a novel metric associated with OS, neurologic death, and need for salvage WBRT after initial DBF following upfront SRS alone.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Patterns of Failure in Patients With Double Hit or Double Expressor Lymphomas: Implications for Radiation Therapy

Lymphomas with MYC and either BLC2 or BCL6 rearrangements or MYC and BCL-2 protein overexpression, classified as double-hit (DHL) or double-expressor (DEL) lymphomas, respectively, are associated with poorer response to standard immunochemotherapy. Optimal therapy is not clear, and little information exists on the contribution of consolidative radiation therapy in these patients. This study describes the patterns of failure of DHL/DEL in relation to initial sites of disease and indications for radiation therapy in unselected diffuse large B-cell lymphoma (DLBCL).

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

A unified finite strain gradient-enhanced micropolar continuum approach for modeling quasi-brittle failure of cohesive-frictional materials

Here, in this work, a novel framework for modeling quasi-brittle crack propagation and shear band dominated failure of cohesive-frictional materials like concrete, mortar, rock, tough ceramics, energetic materials, but also granular materials like sands or powders in terms of a unified continuum approach is proposed. It is based on a combination of the gradient-enhanced continuum with gradients of internal variables for representing quasi-brittle cracking, and the micropolar continuum, accounting for the deformation of the microstructure. For developing the gradient-enhanced micropolar framework, the set of balance equations and the kinematic relations are derived, and the constitutive relations are established in a general manner. The framework is formulated in a geometrically exact setting, based on the thermodynamically sound theory of hyperelasto-plasticity, and the numerical implementation by means of the finite element method is discussed. For assessing the approach, realizations of this new approach in terms of constitutive models for particular materials are developed. They are applied to numerical benchmark examples, investigating various loading conditions, and the obtained results are validated by means of a comparison with experiments from the literature.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Regional Cardiac Sympathetic Nervous System Evaluation Using 123I-mIBG SPECT in Patients with Heart Failure

Heart failure (HF) involves both mechanical and autonomic nervous system dysfunction that can lead to sudden cardiac death. In the failing human heart, there is increased release of norepinephrine from neurons and reduced uptake. Iodine-123–labeled metaiodobenzylguanidine (123I-mIBG) demonstrates reduced global uptake and increased washout associated with increased mortality in HF. This research examined the potential benefits of single-photon emission computed tomography (SPECT) regional quantitation in risk stratification of HF patients and its role in prediction of cardiac morbidity and mortality.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

BISON validation of FeCrAl cladding mechanical failure during simulated reactivity-initiated accident conditions*

Here, a reactivity-initiated accident (RIA) is a postulated design basis accident in light water reactors (LWRs) in which a rapid reactivity insertion induces a fission rate increase and a fuel pellet temperature rise. During RIA, the fuel pellet thermally expands and may cause pellet-cladding mechanical interaction (PCMI). Separate effects PCMI tests were performed on C26M FeCrAl cladding tube samples, introducing biaxial stress via a well understood modified burst test (MBT) system. A high-speed camera in the MBT system captured the projections, covering a 360° view of the cladding deformation and enabling a digital image correlation (DIC) method to quantify the surface strains with high fidelity. Representative hot zero-power RIA mechanical loading conditions were applied to the sample, and the test duration ranged from 20 to 500 ms at an average temperature of 573 K. BISON finite element–based fuel performance code modeling was performed against the high-fidelity DIC data produced from the MBTs. Validation calculations were conducted with 2D models and systematically compared with test data of the burst time, burst pressure, burst hoop strains, and hoop strain rates. Based on the behaviors from the separate effects test, BISON calculations satisfactorily predicted the cladding deformation behaviors. Sensitivity analysis was conducted to identify highly influential mechanical properties responsible for the cladding failure behavior during the MBT experiments. The results highlight the significance of the cladding's mechanical strength in governing cladding strain, followed by the significance of the mechanical interactions between the pellet and the cladding.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

An investigation of the failure modes in U-10Mo monolithic fuel irradiated to high burnup

Here, this study investigated possible failure mode sequences in U-10Mo monolithic fuel irradiated to very-high-burnup. The U-Mo fuel plate used in this study was characterized using scanning electron microscopy (SEM), wavelength dispersive spectroscopy (WDS), and image analysis techniques to investigate how microstructural features may initiate crack formation and propagation through the microstructure, potentially leading to blistering. Distinctly large fission gas pores (FGPs) were observed to preferentially align 5-15µm away from the U-10Mo/Zr interface, parallel to the Zr diffusion barrier. Preferential growth, alignment, and interconnection of FGP could initiate blistering in the fuel plate by creating a fission gas channel, parallel to the U-Mo/Zr interface. FGP alignment in the fuel phase near the U-Mo/Zr interface is believed to be one of the precursors to crack and Type 2 blister formation in monolithic U-Mo fuels. The chemical maps revealed differences in fission product behavior near the U-Mo/Zr interface such that Nd remains in the fuel matrix at the FGP sites. On the other hand, other fission products like Xe and Cs can get trapped in FGPs by Nd in the fuel phase and/or diffuse toward the Zr diffusion barrier.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Mechanical behavior and failure mechanisms of Li-ion battery separators

We determine and compare anisotropic mechanical properties for three types of commercially available Li-ion battery separators: Celgard 2325, Celgard PP2075 dry-processed polymer separators, and DreamWeaver Gold 40 non-woven separator. Significant amount of anisotropy of properties was determined, with the Young's modulus being different by up to a factor of 5 and ultimate strength being different by a factor of 10 between orthogonal directions within a polymer separator layer. Strain rate sensitivity was investigated by applying strain rates ranging from 1•10 -4 s -1 to 0.1 s -1 . Significant strengthening was observed and the strain rate strengthening coefficients were determined for both elastic modulus and yield stress in case of polymer separators. Digital image correlation technique was used to measure and map the strains over the specimen's gage section. A significant strain concentration in bands running perpendicular to the tensile axis was observed in polymer separator samples oriented in transverse direction. Such localized necking allows for extremely high strains close to 300% to develop in the material. Furthermore, the failure mode was remarkably different for all three types of separators which adds additional variable in safe design of Li-ion batteries for prevention of internal short circuits.

25 ENERGY STORAGE↗
DOE OSTI2017

Strain distribution and failure mode of polymer separators for Li-ion batteries under biaxial loading

Deformation of polymer separators for Li-ion batteries has been studied under biaxial tension by using a dome test setup. This deformation mode provides characterization of separator strength under more complex loading conditions, closer representing deformation of an electric vehicle battery during crash event, compared to uniaxial tension or compression. Two polymer separators, Celgard 2325 and Celgard 2075 were investigated by deformation with spheres of three different diameters. Strains in separators were measured in situ by using Digital Image Correlation (DIC) technique. The results show consistent rupture of separators along the machine direction coinciding with areas of high strain accumulation. The critical first principal strain for failure was independent of the sphere diameter and was determined to be approximately 34% and 43% for Celgard 2325 and Celgard 2075 respectively. These values can be taken as a criterion for internal short circuit in a battery following an out-of-plane impact. A Finite Element (FE) model was built with the anisotropic description of separator behavior, derived from tensile tests in orthogonal directions. In conclusion, the results of simulations predicted the response of separator rather well when compared to experimental results for various sizes of rigid sphere.

25 ENERGY STORAGE↗
DOE OSTI2020

Performance degradation due to anodic failure mechanisms in lithium-ion batteries

Here, we report a mechano-chemical model for anodic degradation during fast-charging of nickel-manganese-cobalt (NMC)/graphite (C) cell due to SEI growth, lithium plating/stripping, dead lithium storage, and film fracture of composite SEI and plated lithium film. Degradation of the battery is analyzed for a range of charging rates from 1 to 6 C-rates, and the influence of plating mechanisms – lithium plating and dead lithium deposition and recovery during stripping – on the film resistance of the anode are accounted for in the model. Dynamic evolution of the interfacial properties is modeled using rule-of-mixture approach. Model predictions of plating associated stress fields are used to compute critical energy release rate for film cracking. The results indicate an increased tendency of fracture for thinner SEI film with lithium plating at higher charging rates. The process of reforming the cracked film absorbs a significant portion of the electrode current thereby reducing the cell capacity and plating efficiency. The mechano-chemical model provides an extensive analytical framework for understanding the synergistic coupling of anodic degradation mechanisms, prognosticating conditions of SEI failure, and evaluating the capacity fade and efficiency of lithium-ion battery.

25 ENERGY STORAGE↗
DOE OSTI2024

The battery failure databank: Insights from an open-access database of thermal runaway behaviors of Li-ion cells and a resource for benchmarking risks

The thermal response of Li-ion cells can greatly vary for identical cell designs tested under identical conditions, the distribution of which is costly to fully characterize experimentally. The open-source Battery Failure Databank presented here contains robust, high-quality data from hundreds of abuse tests spanning numerous commercial cell designs and testing conditions. Data was gathered using a fractional thermal runaway calorimeter and contains the fractional breakdown of heat and mass that was ejected, as well as high-speed synchrotron radiography of the internal dynamic response of cells during thermal runaway. The distribution of thermal output, mass ejection, and internal response of commercial cells are compared for different abuse-test conditions, which when normalized on a per amp-hour basis show a strong positive correlation between heat output from cells, the fraction of mass ejected from the cells, their energy- and power-density. Ejected mass was shown to contain 10x more heat per gram than non-ejected mass. The causes of 'outlier' thermal and ejection responses i.e., extreme cases, are elucidated by high-speed radiography which showed how occurrences such as vent clogging can create more hazardous conditions. High-speed radiography also demonstrated how the time-resolved interplay of thermal runaway propagation and mass ejection influences the total heat generated.

25 ENERGY STORAGE↗
DOE OSTI2019

Heavy ion irradiation effects on GaN/AlGaN high electron mobility transistor failure at off-state

We investigate the effects of ion irradiation on AlGaN/GaN high electron mobility electron transistors using in-situ transmission electron microscopy. The experiments are performed inside the microscope to visualize the defects, microstructure and interfaces of ion irradiated transistors during operation and failure. Here, experimental results indicate that heavy ions such as Au 4+ can create a significant number of defects such as vacancies, interstitials and dislocations in the device layer. It is hypothesized that these defects act as charge traps in the device layer and the resulting charge accumulation lowers the breakdown voltage. Sequential energy dispersive X-ray spectroscopy mapping allows us to track individual chemical elements during the experiment, and the results suggest that the electrical degradation in the device layer may originate from oxygen and nitrogen vacancies.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Acute wood smoke exposure is associated with cell-specific hippocampal transcriptomic responses in an accelerated ovarian failure mouse model

Background Wildfire events are increasing in frequency and intensity, and aging individuals demonstrate heightened biological susceptibility to air pollution exposures including increased risk of neurological sequelae. Declining ovarian hormones levels that occur with aging in females along with associated systemic physiological and inflammatory changes may contribute to increased cerebral vulnerability to air pollution, representing a potential but underexplored mechanism. Menopause and the menopausal transition represent a period of profound physiological change that affects cardiovascular, neurological, and immune health. Methods We tested whether peri-menopausal–like hormonal status amplifies hippocampal responses to acute wood smoke (WS) using an ovary-intact, 4-vinylcyclohexene diepoxide (VCD) model of moderate accelerated ovarian failure (AOF) in female C57BL/6 mice. Animals were exposed to HEPA-filtered air (FA) or WS for 4 h/day over 2 consecutive days (∼0.5 mg/m³). Exposure characterization confirmed a complex mixture of combustion products with significant levels of both trace metals and gas release during WS exposure. Results Spatial transcriptomics (10x Visium; n = 4 sections/group) with automated cell-type annotation identified astrocytes, GABAergic and glutamatergic neurons, oligodendrocytes, revealed cell type-specific transcriptional alterations following WS exposure. Distinct transcriptional patterns were observed across all identified neuronal and glial cell populations. Conclusion Together, these findings define a cell-type specific transcriptomic framework describing how WS exposure and ovarian hormone decline interact to influence hippocampal responses and identify potential cellular pathways relevant to hippocampal vulnerability.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗