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At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Intensity-Modulated Radiation Therapy in the Salvage of Locally Recurrent Nasopharyngeal Carcinoma

Purpose: Local recurrences of nasopharyngeal carcinoma (NPC) may be salvaged by reirradiation with conventional techniques, but with significant morbidity. Intensity-modulated radiation therapy (IMRT) may improve the therapeutic ratio by reducing doses to normal tissue. The aim of this study was to address the efficacy and toxicity profile of IMRT for a cohort of patients with locally recurrent NPC. Methods and Materials: Between August 2003 and June 2009, 70 patients with radiologic or pathologically proven locally recurrent NPC were treated with IMRT. The median time to recurrence was 30 months after the completion of conventional radiation to definitive dose. Fifty-seven percent of the tumors were classified asrT3-4. The minimum planned doses were 59.4 to 60 Gy in 1.8- to 2-Gy fractions per day to the gross disease with margins, with or without chemotherapy. Results: The median dose to the recurrent tumor was 70 Gy (range, 50-77.4 Gy). Sixty-five patients received the planned radiation therapy; 5 patients received between 50 and 60 Gy because of acute side effects. With a median follow-up time of 25 months, the rates of 2-year locoregional recurrence-free survival, disease-free survival, and overall survival were 65.8%, 65.8%, and 67.4%, respectively. Moderate to severe late toxicities were noted in 25 patients (35.7%). Eleven patients (15.7%) had posterior nasal space ulceration, 17 (24.3%) experienced cranial nerve palsies, 12 (17.1%) had trismus, and 12 (17.1%) experienced deafness. Extended disease-free interval (relative risk 2.049) and advanced T classification (relative risk 3.895) at presentation were adverse prognostic factors. Conclusion: Reirradiation with IMRT provides reasonable long-term control in patients with locally recurrent NPC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Positron Emission Tomography for Assessing Local Failure After Stereotactic Body Radiotherapy for Non-Small-Cell Lung Cancer

Purpose: We analyzed whether positron emission tomography (PET)/computed tomography standardized uptake values (SUVs) after stereotactic body radiotherapy (SBRT) could predict local recurrence (LR) in non-small-cell lung cancer (NSCLC). Methods and Materials: This study comprised 128 patients with Stage I (n = 68) or isolated recurrent/secondary parenchymal (n = 60) NSCLC treated with image-guided SBRT to 50 Gy over 4 consecutive days; prior radiotherapy was allowed. PET/computed tomography scans were obtained before therapy and at 1 to 6 months after therapy, as well as subsequently as clinically indicated. Continuous variables were analyzed with Kruskal-Wallis tests and categorical variables with Pearson chi-square or Fisher exact tests. Actuarial local failure rates were calculated with the Kaplan-Meier method. Results: At a median follow-up of 31 months (range, 6-71 months), the actuarial 1-, 2-, and 3-year local control rates were 100%, 98.5%, and 98.5%, respectively, in the Stage I group and 95.8%, 87.6%, and 85.8%, respectively, in the recurrent group. The cumulative rates of regional nodal recurrence and distant metastasis were 8.8% (6 of 68) and 14.7% (10 of 68), respectively, for the Stage I group and 11.7% (7 of 60) and 16.7% (10 of 60), respectively, for the recurrent group. Univariate analysis showed that SUVs obtained 12.1 to 24 months after treatment for the Stage I group (p = 0.007) and 6.1 to 12 months and 12.1 to 24 months after treatment for the recurrent group were associated with LR (p < 0.001 for both). Of the 128 patients, 17 (13.3%) had ipsilateral consolidation after SBRT but no elevated metabolic activity on PET; none had LR. The cutoff maximum SUV of 5 was found to have 100% sensitivity, 91% specificity, a 50% positive predictive value, and a 100% negative predictive value for predicting LR. Conclusions: PET was helpful for distinguishing SBRT-induced consolidation from LR. SUVs obtained more than 6 months after SBRT for NSCLC were associated with local failure. A maximum SUV greater than 5, especially at more than 6 months after SBRT, should prompt biopsy to rule out LR.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Adaptive/Nonadaptive Proton Radiation Planning and Outcomes in a Phase II Trial for Locally Advanced Non-small Cell Lung Cancer

Purpose: To analyze dosimetric variables and outcomes after adaptive replanning of radiation therapy during concurrent high-dose protons and chemotherapy for locally advanced non-small cell lung cancer (NSCLC). Methods and Materials: Nine of 44 patients with stage III NSCLC in a prospective phase II trial of concurrent paclitaxel/carboplatin with proton radiation [74 Gy(RBE) in 37 fractions] had modifications to their original treatment plans after re-evaluation revealed changes that would compromise coverage of the target volume or violate dose constraints; plans for the other 35 patients were not changed. We compared patients with adaptive plans with those with nonadaptive plans in terms of dosimetry and outcomes. Results: At a median follow-up of 21.2 months (median overall survival, 29.6 months), no differences were found in local, regional, or distant failure or overall survival between groups. Adaptive planning was used more often for large tumors that shrank to a greater extent (median, 107.1 cm{sup 3} adaptive and 86.4 cm{sup 3} nonadaptive; median changes in volume, 25.3% adaptive and 1.2% nonadaptive; P<.01). The median number of fractions delivered using adaptive planning was 13 (range, 4-22). Adaptive planning generally improved sparing of the esophagus (median absolute decrease in V{sub 70}, 1.8%; range, 0%-22.9%) and spinal cord (median absolute change in maximum dose, 3.7 Gy; range, 0-13.8 Gy). Without adaptive replanning, target coverage would have been compromised in 2 cases (57% and 82% coverage without adaptation vs 100% for both with adaptation); neither patient experienced local failure. Radiation-related grade 3 toxicity rates were similar between groups. Conclusions: Adaptive planning can reduce normal tissue doses and prevent target misses, particularly for patients with large tumors that shrink substantially during therapy. Adaptive plans seem to have acceptable toxicity and achieve similar local, regional, and distant control and overall survival, even in patients with larger tumors, vs nonadaptive plans.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Long-term Follow-up Results of a Multi-institutional Phase 2 Study of Concurrent Chemoradiation Therapy for Locally Advanced Cervical Cancer in East and Southeast Asia

Purpose: To report the long-term survival and toxicity of a multi-institutional phase 2 study of concurrent chemoradiation therapy (CCRT) for locally advanced cervical cancer in east and southeast Asia. Methods and Materials: Ten institutions from 8 Asian countries participated in the study. Between April 2003 and March 2006, 120 patients (60 with bulky stage IIB and 60 with stage IIIB) were treated with CCRT. Radiation therapy consisted of pelvic external beam radiation therapy and either high-dose-rate or low-dose-rate intracavitary brachytherapy. Five cycles of weekly cisplatin (40 mg/m{sup 2}) were administered during the course of radiation therapy. Treatment results were evaluated by the rates of local control, overall survival, and late toxicities. Results: Median follow-up was 63.7 months, and the follow-up rate at 5 years was 98%. The 5-year local control and overall survival rates for all patients were 76.8% and 55.1%, respectively. The 5-year rates of major late toxicities of the rectum and bladder were 7.9% and 0%, respectively. Conclusions: The long-term results have suggested that CCRT is safe and effective for patients with locally advanced cervical cancer in east and southeast Asia. However, further efforts are needed to improve overall survival.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Automated Patient Identification and Localization Error Detection Using 2-Dimensional to 3-Dimensional Registration of Kilovoltage X-Ray Setup Images

Purpose: To determine whether kilovoltage x-ray projection radiation therapy setup images could be used to perform patient identification and detect gross errors in patient setup using a computer algorithm. Methods and Materials: Three patient cohorts treated using a commercially available image guided radiation therapy (IGRT) system that uses 2-dimensional to 3-dimensional (2D-3D) image registration were retrospectively analyzed: a group of 100 cranial radiation therapy patients, a group of 100 prostate cancer patients, and a group of 83 patients treated for spinal lesions. The setup images were acquired using fixed in-room kilovoltage imaging systems. In the prostate and cranial patient groups, localizations using image registration were performed between computed tomography (CT) simulation images from radiation therapy planning and setup x-ray images corresponding both to the same patient and to different patients. For the spinal patients, localizations were performed to the correct vertebral body, and to an adjacent vertebral body, using planning CTs and setup x-ray images from the same patient. An image similarity measure used by the IGRT system image registration algorithm was extracted from the IGRT system log files and evaluated as a discriminant for error detection. Results: A threshold value of the similarity measure could be chosen to separate correct and incorrect patient matches and correct and incorrect vertebral body localizations with excellent accuracy for these patient cohorts. A 10-fold cross-validation using linear discriminant analysis yielded misclassification probabilities of 0.000, 0.0045, and 0.014 for the cranial, prostate, and spinal cases, respectively. Conclusions: An automated measure of the image similarity between x-ray setup images and corresponding planning CT images could be used to perform automated patient identification and detection of localization errors in radiation therapy treatments.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

A New Treatment Paradigm: Neoadjuvant Radiosurgery Before Surgical Resection of Brain Metastases With Analysis of Local Tumor Recurrence

Purpose: Resected brain metastases (BM) require radiation therapy to reduce local recurrence. Whole brain radiation therapy (WBRT) reduces recurrence, but with potential toxicity. Postoperative stereotactic radiosurgery (SRS) is a strategy without prospective data and problematic target delineation. SRS delivered in the preoperative setting (neoadjuvant, or NaSRS) allows clear target definition and reduction of intraoperative dissemination of tumor cells. Methods and Materials: Our treatment of resectable BM with NaSRS was begun in 2005. Subsequently, a prospective trial of NaSRS was undertaken. A total of 47 consecutively treated patients (23 database and 24 prospective trial) with a total of 51 lesions were reviewed. No statistical difference was observed between the 2 cohorts, and they were combined for analysis. The median follow-up time was 12 months (range, 1-58 months), and the median age was 57. A median of 1 day elapsed between NaSRS and resection. The median diameter of lesions was 3.04 cm (range, 1.34-5.21 cm), and the median volume was 8.49 cc (range, 0.89-46.7 cc). A dose reduction strategy was used, with a median dose of 14 Gy (range, 11.6-18 Gy) prescribed to 80% isodose. Results: Kaplan-Meier overall survival was 77.8% and 60.0% at 6 and 12 months. Kaplan-Meier local control was 97.8%, 85.6%, and 71.8% at 6, 12, and 24 months, respectively. Five of 8 failures were proved pathologically without radiation necrosis. There were no perioperative adverse events. Ultimately, 14.8% of the patients were treated with WBRT. Local failure was more likely with lesions >10 cc (P=.01), >3.4 cm (P=.014), with a trend in surface lesions (P=.066) and eloquent areas (P=.052). Six of the 8 failures had an obvious dural attachment or proximity to draining veins. Conclusions: NaSRS can be performed safely and effectively with excellent results without documented radiation necrosis. Local control was excellent even in the setting of large (>3 cm) lesions. The strong majority of patients were able to avoid WBRT. NaSRS merits consideration in a multi-institution trial.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

High-Dose-Rate Brachytherapy Boost Effect on Local Tumor Control in Young Women With Breast Cancer

Purpose: To evaluate the local control rate and complications of a single fraction of high-dose-rate brachytherapy (HDR BT) boost in women aged 45 yeas and younger after breast-conserving therapy. Methods and Materials: Between 1999 and 2007, 167 patients between the ages of 26 and 45 years old (72 were 40 years old or younger), with stages T1 to T2 invasive breast cancer with disease-free margin status of at least 5 mm after breast-conserving surgery received 46 to 50 Gy whole-breast irradiation plus a 7-Gy HDR-BT boost (“fast boost”). An axillary dissection was performed in 72.5% of the patients and sentinel lymph node biopsy in 27.5%. A supraclavicular area was irradiated in 19% of the patients. Chemotherapy was used in 86% of the patients and hormone treatment in 77%. Clinical nodes were present in 18% and pathological nodes in 29%. The pathological stage was pT0: 5%, pTis: 3%, pT1: 69% and pT2: 23%. Intraductal component was present in 40% and 28% were G3. Results: At a median follow-up of 92 months, 9 patients relapsed on the margin of the implant, and 1 patient in another quadrant, resulting in a 10-year local relapse rate of 4.3% and a breast relapse rate of 4.9%, with breast preservation in 93.4%; no case of mastectomy due to poor cosmesis arose. Actuarial 5- and 10-year disease-free, cause-specific, and overall survival rates were 87.9% and 85.8%, and 92.1% and 88.4%, and 92.1% and 87.3%, respectively. In a univariate analysis, triple-negative cases and negative hormone receptors did worse, but in a multivariate analysis, only the last factor was significant for local and breast control. Asymptomatic fibrosis G2 was recorded in 3 cases, and there were no other late complications. Cosmetic results were good to excellent in 97% of cases. Conclusions: A single dose of 7 Gy using the fast-boost technique is well tolerated, with a low rate of late complications and improved local tumor control in women aged 45 and younger, compared to published data. This approach is recommended in breast-preserving treatment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Outcome According to Elective Pelvic Radiation Therapy in Patients With High-Risk Localized Prostate Cancer: A Secondary Analysis of the GETUG 12 Phase 3 Randomized Trial

Purpose: The role of pelvic elective nodal irradiation (ENI) in the management of prostate cancer is controversial. This study analyzed the role of pelvic radiation therapy (RT) on the outcome in high-risk localized prostate cancer patients included in the Groupe d'Etude des Tumeurs Uro-Genitales (GETUG) 12 trial. Methods and Materials: Patients with a nonpretreated high-risk localized prostate cancer and a staging lymphadenectomy were randomly assigned to receive either goserelin every 3 months for 3 years and 4 cycles of docetaxel plus estramustine or goserelin alone. Local therapy was administered 3 months after the start of systemic treatment. Performance of pelvic ENI was left to the treating physician. Only patients treated with primary RT were included in this analysis. The primary endpoint was biochemical progression-free survival (bPFS). Results: A total of 413 patients treated from 2002 to 2006 were included, of whom 358 were treated using primary RT. A total of 208 patients received pelvic RT and 150 prostate-only RT. Prostate-specific antigen (PSA) concentration, Gleason score, or T stage did not differ according to performance of pelvic RT; pN+ patients more frequently received pelvic RT than pN0 patients (P<.0001). Median follow-up was 8.8 years. In multivariate analysis, bPFS was negatively impacted by pN stage (hazard ratio [HR]: 2.52 [95% confidence interval [CI]: 1.78-3.54], P<.0001), Gleason score 8 or higher (HR: 1.41 [95% CI: 1.03-1.93], P=.033) and PSA higher than 20 ng/mL (HR: 1.41 [95% CI: 1.02-1.96], P=.038), and positively impacted by the use of chemotherapy (HR: 0.66 [95% CI: 0.48-0.9], P=.009). There was no association between bPFS and use of pelvic ENI in multivariate analysis (HR: 1.10 [95% CI: 0.78-1.55], P=.60), even when analysis was restricted to pN0 patients (HR: 0.88 [95% CI: 0.59-1.31], P=.53). Pelvic ENI was not associated with increased acute or late patient reported toxicity. Conclusions: This unplanned analysis of a randomized trial failed to demonstrate a benefit of pelvic ENI on bPFS in high-risk localized prostate cancer patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Proton Therapy as Salvage Treatment for Local Relapse of Prostate Cancer Following Cryosurgery or High-Intensity Focused Ultrasound

Purpose: Local recurrence of prostate cancer after cryosurgery (CS) and high-intensity focused ultrasound (HIFU) is an emerging problem for which optimal management is unknown. Proton therapy (PT) may offer advantages over other local therapeutic options. This article reviews a single institution's experience using PT for salvage of local recurrent disease after HIFU or CS. Methods and Materials: We reviewed the medical records of 21 consecutive patients treated with salvage PT following a local recurrence of prostate cancer after CS (n=12) or HIFU (n=9) between January 2007 and July 2014. Patients were treated to a median dose of 74 Gy(relative biological effectiveness [RBE]; range: 74-82 Gy[RBE]) and 8 patients received androgen deprivation therapy with radiation therapy. Patients were evaluated for quality of life (QOL) by using the Expanded Prostate Index Composite questionnaire and toxicity by using Common Terminology Criteria for Adverse Events, version 3.0, weekly during treatment, every 6 months for 2 years after treatment, and then annually. Results: Median follow-up was 37 months (range: 6-95 months). The 3-year biochemical progression-free survival (bPFS) rate was 77%. The 3-year grade 3 toxicity rate was 17%; however, 2 of these patients had pre-existing grade 3 GU toxicities from their HIFU/CRYO prior to PT. At 1 year, bowel summary, urinary incontinence, and urinary obstructive QOL scores declined, but only the bowel QOL score at 12 months met the minimally important difference threshold. Conclusions: PT achieved a high rate of bPFS with acceptable toxicity and minimal changes in QOL scores compared with baseline pre-PT functions. Although most patients have done fairly well, the study size is small, follow-up is short, and early results suggest that outcomes with PT for salvage after HIFU or CS failure are inferior to outcomes with PT given in the de novo setting with respect to disease control, toxicity, and QOL.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Carbon Ion Radiation Therapy With Concurrent Gemcitabine for Patients With Locally Advanced Pancreatic Cancer

Purpose: To determine, in the setting of locally advanced pancreatic cancer, the maximum tolerated dose of carbon ion radiation therapy (C-ion RT) and gemcitabine dose delivered concurrently and to estimate local effect and survival. Methods and Materials: Eligibility included pathologic confirmation of pancreatic invasive ductal carcinomas and radiographically unresectable disease without metastasis. Concurrent gemcitabine was administered on days 1, 8, and 15, and the dose levels were escalated from 400 to 1000 mg/m{sup 2} under the starting dose level (43.2 GyE) of C-ion RT. The dose levels of C-ion RT were escalated from 43.2 to 55.2 GyE at 12 fractions under the fixed recommended gemcitabine dose determined. Results: Seventy-six patients were enrolled. Among the 72 treated patients, dose-limiting toxicity was observed in 3 patients: grade 3 infection in 1 patient and grade 4 neutropenia in 2 patients. Only 1 patient experienced a late grade 3 gastric ulcer and bleeding 10 months after C-ion RT. The recommended dose of gemcitabine with C-ion RT was found to be 1000 mg/m{sup 2}. The dose of C-ion RT with the full dose of gemcitabine (1000 mg/m{sup 2}) was safely increased to 55.2 GyE. The freedom from local progression rate was 83% at 2 years using the Response Evaluation Criteria in Solid Tumors. The 2-year overall survival rates in all patients and in the high-dose group with stage III (≥45.6 GyE) were 35% and 48%, respectively. Conclusions: Carbon ion RT with concurrent full-dose gemcitabine was well tolerated and effective in patients with unresectable locally advanced pancreatic cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

The international implications of national and local coordination on building energy codes: Case studies in six cities

Building energy efficiency is an important strategy for reducing greenhouse gas emissions globally. In fact, 55 countries have included building energy efficiency in their Nationally Determined Contributions (NDCs) under the Paris Agreement. This research uses building energy code implementation in six cities across different continents as case studies to assess what it may take for countries to implement the ambitions of their energy efficiency goals. Specifically, we look at the cases of Bogota, Colombia; Da Nang, Vietnam; Eskisehir, Turkey; Mexico City, Mexico; Rajkot, India; and Tshwane, South Africa, all of which are “deep dive” cities under the Sustainable Energy for All's Building Efficiency Accelerator. The research focuses on understanding the baseline with existing gaps in implementation and coordination. The methodology used a combination of surveys on code status and interviews with stakeholders at the local and national level, as well as review of published documents. We looked at code development, implementation, and evaluation. The cities are all working to improve implementation, however, the challenges they currently face include gaps in resources, capacity, tools, and institutions to check for compliance. Better coordination between national and local governments could help improve implementation, but that coordination is not yet well established. For example, all six of the cities reported that there was little to no involvement of local stakeholders in development of the national code; only one city reported that it had access to national funding to support code implementation. More robust coordination could better link cities with capacity building and funding for compliance, and ensure that the code reflects local priorities. By understanding gaps in implementation, it can also help in designing more targeted interventions to scale up energy savings.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2018

Enforcing the Courant–Friedrichs–Lewy condition in explicitly conservative local time stepping schemes

In this study, an optimally efficient explicit numerical scheme for solving fluid dynamics equations, or any other parabolic or hyperbolic system of partial differential equations, should allow local regions to advance in time with their own, locally constrained time steps. However, such a scheme can result in violation of the Courant-Friedrichs-Lewy (CFL) condition, which is manifestly non-local. Although the violations can be considered to be "weak" in a certain sense and the corresponding numerical solution may be stable, such calculation does not guarantee the correct propagation speed for arbitrary waves . We use an experimental fluid dynamics code that allows cubic "patches" of grid cells to step with independent, locally constrained time steps to demonstrate how the CFL condition can be enforced by imposing a condition on the time steps of neighboring patches. We perform several numerical tests that illustrate errors introduced in the numerical solutions by weak CFL condition violations and show how strict enforcement of the CFL condition eliminates these errors. In all our tests the strict enforcement of the CFL condition does not impose a significant performance penalty.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

A business approach to climate adaptation in local communities

Climate change poses risks to the assets and operations of businesses. They can anticipate, prepare for, and adapt to the potential impacts of climate change by focusing on modifying their own internal operations. But businesses can find additional opportunities to adapt by examining their relationships with local governments. Businesses provide critical services to the communities in which they are located, and also benefit from services provided by the local governments. This symbiotic relationship is an important consideration for businesses as they work to adapt to a changing climate. By thinking broadly about how working with local governments can influence their resilience, businesses may be able to uncover additional adaptation opportunities and enhance their adaption efforts in ways they may not be able to achieve on their own. Here, this paper includes two case studies of businesses that pursued adaptation efforts with local, state, or federal government officials to provide real-world context for the symbiotic relationships that exist between the private and public sectors in communities.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Local structural mechanism for enhanced energy storage properties in heterovalent doped NaNbO 3 ceramics

In recent years, there is a growing interest for new lead-free oxides with reversible antiferroelectric (AFE)-ferroelectric (FE) phase transition for high-power energy-storage applications. NaNbO 3 -based ceramics are particularly attractive due to their easy synthesis and cost-effectiveness. In order to stabilize reversible AFE-FE phase transition, NaNbO 3 is doped with a combination of heterovalent substitutions, although the underlying structural mechanism for the same is poorly understood. Here, we investigated local and average structures of Ca/Zr doped NaNbO 3 using neutron total scattering. Here, we show that Ca/Zr doping increases the average AFE phase (Pbma) fraction, however, the material remains as a composite of both FE (P2 1 ma) and AFE regions. Analysis of local structure suggests that increase in the long-range AFE phase results from more extensive twinning of local FE regions, due to introduced charge disorder. We propose that enhanced energy-storage properties of Ca/Zr-doped NaNbO 3 arises from localized twin boundary motion between the defect-induced pinning centers.

25 ENERGY STORAGE↗
DOE OSTI2021

Local prediction of Laser Powder Bed Fusion porosity by short-wave infrared imaging thermal feature porosity probability maps

We report that local thermal history can significantly vary in parts during metal Additive Manufacturing (AM), leading to local defects. However, the sequential layer-by-layer nature of AM facilitates in-situ part voxelmetric observations that can be used to detect and correct these defects for part qualification and quality control. The challenge is to relate this local radiometric data with local defect information to estimate process error likelihood in future builds. This paper uses a Short-Wave Infrared (SWIR) camera to record the temperature history for parts manufactured with Laser Powder Bed Fusion (LPBF) processes. The porosity from a cylindrical specimen is measured by ex-situ micro-computed tomography (μCT). Specimen data from the SWIR camera, combined with the μCT data, are used to generate thermal feature-based porosity probability maps. The porosity predictions made by various SWIR thermal feature-porosity probability maps of a specimen with a complex geometry are scored against the true porosity obtained via μCT. The receiver operating characteristic curves constructed from the predictions for the complex sample demonstrate the porosity probability mapping methodology’s potential for in-situ based porosity detection.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Optimizing Bendability and Hardness of Age-Hardenable Aluminum Sheets through Local Thermo-Mechanical Processing

This paper introduces a novel thermo-mechanical process to modify the local mechanical properties of 6xxx aluminum (Al-Mg-Si-Cu) alloy sheets. In this process, two pairs of rollers travel along the length of a sheet while locally bending and unbending it so that the final shape and thickness of the sheet remains unchanged. Room temperature bending/unbending (B/U) produces a deformation gradient through thickness and local hardening in both T4 and T6 sheets (with 41% and 18% greater Vickers hardness, respectively). High temperature bending/unbending performed at ~ 500°C via induction heating, produces significant improvements in local formability as measured by bend testing. Formability levels equivalent to the as-received T4 temper are achieved within the processed zones of T6 sheets with bend angles of ~ 150°, without disturbing the T6 temper in the remainder of the sheet. Finite element simulations and characterization explained the mechanical property improvements and the heterogenous microstructure with weakened Cube texture. Due to its similarity with the roller hemming process, and its compact dimensions, the apparatus developed for B/U has the potential for seamless integration with roller hemming robots to selectively process high strength aluminum sheet materials within mass-production settings.

Efe, Mert [BATTELLE (PACIFIC NW LAB)]↗
DOE OSTI2014

Local structure around the flux pinning centers in superconducting niobium silicon oxynitride (Nb{sub 0.87}Si{sub 0.09}□{sub 0.04})(N{sub 0.87}O{sub 0.13})

The superconducting transition temperature of niobium silicon oxynitride (Nb{sub 0.87}Si{sub 0.09}□{sub 0.04})(N{sub 0.87}O{sub 0.13}) exhibits a gradual reduction from 16.8 K to around 11 K under an increasing applied magnetic field of up to 14 T. This relatively small T{sub c} reduction under an applied magnetic field suggests a robustness of its superconducting behavior in comparison to that in the parent niobium oxynitride. It was similar to the flux pinning effect observed in the large magnetic hysteresis of the niobium-silicon oxynitrides in our previous study. Both Si K-edge XANES and {sup 29}Si MAS-NMR indicated that the local structure of pinning centers around the silicon atoms close to cationic vacancies was similar to that of Si in amorphous SiO{sub 2} in the rock-salt structure of niobium oxynitride. - Graphical abstract: Potential energy scan of the Si atom in the most stable Si{sub 3}□O{sub 3}N cube around the vacancy in our preliminary simulation on niobium silicon oxynitride (Nb{sub 0.87}Si{sub 0.09}□{sub 0.04})(N{sub 0.87}O{sub 0.13}). A possible distortion of the Si atom was suggested from its octahedral towards tetrahedral position forming the local structure similar to that in amorphous SiO{sub 2}. Display Omitted - Highlights: • Critical current density was enhanced in superconducting niobium oxynitride. • The robustness was introduced by forming rock-salt type niobium silicon oxynitride. • The silicon atom had a local structure similar to that in amorphous SiO{sub 2} in the rock-salt type lattice. • The local structure was formed together with its neighboring cationic vacancy. • It contributed as the flux pinning center in the NbSiNO.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Local orderings in long-range-disordered bismuth-layered intergrowth structure

A series of intergrowth bismuth-layered (Bi{sub 3}TiNbO{sub 9}){sub 2}(Bi{sub 4}Ti{sub 3}O{sub 12}) (2{sub 2}3) ceramics were prepared by conventional solid-state reaction to study the characteristics of the local orderings in long-range-disordered intergrowth structures. High-resolution high-angle annular dark-field (HAADF) imaging reveals the intergrowth structure composed of mixtures of -23-, -223-, -2223- and -22- sequences, while the -223- structure is the thermodynamic stable state of this intergrowth system. It was confirmed by the crystals of recurrent -223- structure prepared by self-flux method and the nature of the local ordering was discussed from their differences in repeating units. The statistics show that when repeating units reach 4 or higher, the independent -223- intergrowth ordering emerges clearly among the competing associated orderings. We infer it is the kinetic factor that induces local compositional variance to result in long-range disordered intergrowth structures. - Graphical abstract: The long-range-disordered intergrowth structure in a (Bi{sub 3}TiNbO{sub 9}){sub 2}(Bi{sub 4}Ti{sub 3}O{sub 12}) (2{sub 2}3) grain, which is composed of various types of local orderings, such as -22-, -23- and -223-. - Highlights: • The characteristic of the long-range-disordered (Bi{sub 3}TiNbO{sub 9}){sub 2}(Bi{sub 4}Ti{sub 3}O{sub 12}) (2{sub 2}3) structure was statistically analyzed, and the ordered -223- structure was speculated to be the thermodynamic stable state of the system. • The crystals of the -223- structure were successfully prepared for the first time by self-melt method. • The lower limit of the repeating units (L) to uniquely determine an independent intergrowth structure was speculated to be L=4. • The analysis inferred that the kinetic process is the controlling factor to limit the structural continuity and induce the long-range-disordered intergrowth structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗