Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “functionally graded material”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Effect of the Maximum Dose on White Matter Fiber Bundles Using Longitudinal Diffusion Tensor Imaging

Purpose: Previous efforts to decrease neurocognitive effects of radiation focused on sparing isolated cortical structures. We hypothesize that understanding temporal, spatial, and dosimetric patterns of radiation damage to whole-brain white matter (WM) after partial-brain irradiation might also be important. Therefore, we carried out a study to develop the methodology to assess radiation therapy (RT)–induced damage to whole-brain WM bundles. Methods and Materials: An atlas-based, automated WM tractography analysis was implemented to quantify longitudinal changes in indices of diffusion tensor imaging (DTI) of 22 major WM fibers in 33 patients with predominantly low-grade or benign brain tumors treated by RT. Six DTI scans per patient were performed from before RT to 18 months after RT. The DTI indices and planned doses (maximum and mean doses) were mapped onto profiles of each of 22 WM bundles. A multivariate linear regression was performed to determine the main dose effect as well as the influence of other clinical factors on longitudinal percentage changes in axial diffusivity (AD) and radial diffusivity (RD) from before RT. Results: Among 22 fiber bundles, AD or RD changes in 12 bundles were affected significantly by doses (P<.05), as the effect was progressive over time. In 9 elongated tracts, decreased AD or RD was significantly related to maximum doses received, consistent with a serial structure. In individual bundles, AD changes were up to 11.5% at the maximum dose locations 18 months after RT. The dose effect on WM was greater in older female patients than younger male patients. Conclusions: Our study demonstrates for the first time that the maximum dose to the elongated WM bundles causes post-RT damage in WM. Validation and correlative studies are necessary to determine the ability and impact of sparing these bundles on preserving neurocognitive function after RT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Adjuvant Intensity Modulated Whole-Abdominal Radiation Therapy for High-Risk Patients With Ovarian Cancer (International Federation of Gynecology and Obstetrics Stage III): First Results of a Prospective Phase 2 Study

Purpose: To assess treatment tolerance and toxicity rates of consolidative whole-abdominal radiation therapy (WART) following cytoreductive surgery and carboplatin/paclitaxel chemotherapy in high-risk patients with advanced ovarian cancer (International Federation of Gynecology and Obstetrics stage III) using intensity modulated radiation therapy. Methods and Materials: The OVAR-IMRT-02 study is a multicenter, single-arm, phase 2 trial. Twenty patients with optimally debulked ovarian cancer (International Federation of Gynecology and Obstetrics stage III) with complete remission after chemotherapy were treated with intensity modulated WART as a consolidation therapy. A total dose of 30 Gy in 20 fractions of 1.5 Gy was applied to the entire peritoneal cavity. The primary endpoint was treatment tolerability, defined as lack of any Common Terminology Criteria for Adverse Events grade 4 toxicity within 10 weeks after start of treatment; secondary objectives were acute and chronic toxicity, quality of life, rates of therapy disruption and abortion, and progression-free and overall survival. Results: Intensity modulated WART resulted in excellent coverage of the whole peritoneal cavity, with effective sparing of all organs at risk. The primary analysis included all 20 enrolled patients, of whom 19 did not experience Common Terminology Criteria for Adverse Events grade 4 toxicity. Only 1 patient experienced acute grade 4 hematologic toxicity. Thus, the tolerability rate of intensity modulated WART was significantly higher than 70%. No gastrointestinal acute toxicities higher than grade 2 have been observed. During WART, mean global health status decreased by 18.1 points (95% confidence interval 7.1, 29.0). Six weeks after WART, global health status had already increased, with a mean score difference of 4.6 (95% confidence interval −11.1, 20.4) compared with baseline. Similar characteristics were observed for all function scale scores. Conclusion: Intensity modulated WART after aggressive surgery and carboplatin/paclitaxel chemotherapy is associated with an acceptable risk of acute toxicity and a treatment tolerability rate significantly higher than 70%. Together with our knowledge about clinical feasibility, meaning excellent coverage of the planning target volume and effective sparing of organs at risk, intensity modulated WART could offer a new therapeutic option for consolidation treatment of patients with advanced ovarian cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

External Beam Radiotherapy for Prostate Cancer: Urinary Outcomes for Men With High International Prostate Symptom Scores (IPSS)

Purpose: To report the urinary outcome of men treated for prostate cancer with external beam radiotherapy (EBRT) who have pretreatment obstructive urinary symptoms (International Prostate Symptom Score [IPSS] {>=}15). Methods and Materials: We treated 368 patients with EBRT for localized prostate cancer, and pre- and post-radiotherapy (RT) IPSSs were recorded. In total, 80 men had an IPSS {>=}15, 48% of whom were taking genitourinary (GU) medications before RT. The IPSS was followed over time and analyzed as a pretreatment factor against Radiation Therapy Oncology Group acute and late GU toxicity. Results: The median follow-up was 44 months. Among men with a pre-RT IPSS {>=}15, the median IPSS at baseline, first follow-up, and last follow-up was 18 (range, 15 to 34), 17 (range, 0 to 32), and 13 (range, 0 to 34), respectively. The mean patient declines in IPSS from baseline to first and last follow-up were -3.6 points (p < 0.0004) and -6.9 points (p < 0.0001), respectively. At last follow-up, 43 men (54%) took GU medications. Pre-RT IPSS {>=}15 vs. {<=}14 was associated with a higher incidence of Grade {>=}2 acute GU toxicity (64% vs. 42%, p = 0.0005), and 4-year freedom from Grade {>=}2 late GU toxicity was 38% vs. 64% (p < 0.0001). There was no greatly increased risk of Grade {>=}3 late GU toxicity for men with IPSS {>=}15 (4-year freedom from Grade {>=}3 late GU toxicity of 90% vs. 96%, p = 0.0964). Conclusions: Although the improvement is not immediate, men with moderate to severe obstructive GU symptoms can have improvement in urinary function after EBRT, without significant risk for severe morbidity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Phase 1 Trial of Sorafenib and Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma

Purpose: To determine the maximally tolerated dose of sorafenib delivered before, during, and after stereotactic body radiation therapy (SBRT) in hepatocellular carinoma (HCC). Methods and Materials: Eligible patients had locally advanced Child-Pugh class A HCC, showed Eastern Cooperative Oncology Group performance status 0-1, and were ineligible for standard local-regional therapies. Sorafenib was dose escalated in 2 strata: (1) low effective irradiated liver volume (veff) < 30% and (2) high veff 30%to 60%. Sorafenib (400 mg daily = dose level 1) was administered for 12 weeks, with 6 fractions SBRT delivered weeks 2 and 3, and escalation to full dose (400 mg twice daily) after 12 weeks as tolerated. Standard 3 + 3 cohorts with dose escalation of sorafenib were planned. Results: Sixteen patients (4 low veff, median dose 51 Gy; 12 high veff, median dose 33 Gy) were treated at 2 sorafenib dose levels. Of those patients 75% were had Barcelona Clinic Liver Cancer stage C, and 63% had main branch portal vein invasion. In the low veff stratum, no dose-limiting toxicities (DLTs) were observed in 4 patients treated with SBRT and sorafenib 400 mg. Inb the high veff stratum: 2 of 3 evaluable patients treated with sorafenib 400 mg experienced DLT (grade 3 large bowel bleed and grade 4 bowel obstruction 51 and 27 days, respectively, after SBRT). One of 6 evaluable patients at dose level −1 (200 mg once daily) experienced a grade 3 tumor rupture at week 5. Median overall survival and in-field local progression have not been reached. Worsening of Child-Pugh liver function class was seen in 6 of 12 patients in the high veff stratum. Conclusions: Significant toxicity was observed in the high veff stratum, and concurrent SBRT with sorafenib is not recommended outside a clinical trial.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Kinetic Modeling of a Silicon Refining Process in a Moist Hydrogen Atmosphere

We developed a kinetic model that considers both silicon loss and boron removal in a metallurgical grade silicon refining process. This model was based on the hypotheses of reversible reactions. The reaction rate coefficient kept the same form but error of terminal boron concentration could be introduced when relating irreversible reactions. Experimental data from published studies were used to develop a model that fit the existing data. At 1500 °C, our kinetic analysis suggested that refining silicon in a moist hydrogen atmosphere generates several primary volatile species, including SiO, SiH, HBO, and HBO{sub 2}. Using the experimental data and the kinetic analysis of volatile species, we developed a model that predicts a linear relationship between the reaction rate coefficient k and both the quadratic function of p(H{sub 2}O) and the square root of p(H{sub 2}). Moreover, the model predicted the partial pressure values for the predominant volatile species and the prediction was confirmed by the thermodynamic calculations, indicating the reliability of the model. We believe this model provides a foundation for designing a silicon refining process with a fast boron removal rate and low silicon loss.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Clinical Outcomes of Definitive Intensity-Modulated Radiation Therapy With Fluorodeoxyglucose-Positron Emission Tomography Simulation in Patients With Locally Advanced Cervical Cancer

Purpose: This study aimed to evaluate the toxicity and clinical outcomes for cervical cancer patients treated definitively with intensity-modulated radiation therapy (IMRT) compared with non-IMRT treatment. Methods and Materials: This prospective cohort study included 452 patients with newly diagnosed cervical cancer treated with curative intent (135 IMRT and 317 non-IMRT). Treatment involved external irradiation and brachytherapy, and 85% of patients received concurrent chemotherapy. All IMRT patients underwent an F-18 fluorodeoxyglucose positron emission tomography (FDG-PET/CT) simulation. A 3-month post-therapy PET was obtained to evaluate treatment response. Toxicity was scored by the Common Terminology Criteria for Adverse Events Version 3.0. Results: The IMRT and non-IMRT groups had similar stage distribution and histology. For all patients, the post-therapy FDG-PET response correlated with overall recurrence risk (p < 0.0001) and cause-specific survival (p < 0.0001). Post-treatment FDG-PET findings were not significantly different between the IMRT and non-IMRT patients (p = 0.9774). The mean follow-up for all patients alive at the time of last follow-up was 52 months (72 months non-IMRT, 22 months IMRT). At last follow-up, 178 patients (39 IMRT, 139 non-IMRT) had developed a recurrence. The difference in recurrence-free survival between the two groups did not reach statistical significance (p = 0.0738), although the IMRT group showed better overall and cause-specific survivals (p < 0.0001). Of the patients, 62 patients (8 IMRT and 54 non-IMRT) developed Grade 3 or greater bowel or bladder complications, and by cumulative hazard function analysis the risk was significantly less for patients treated with IMRT (p = 0.0351). Conclusion: Cervical cancer patients treated with FDG-PET/CT-guided IMRT have improved survival and less treatment-related toxicity compared with patients treated with non-IMRT radiotherapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Intensity Modulated Radiation Therapy for Early-Stage Primary Gastric Diffuse Large B-Cell Lymphoma: Dosimetric Analysis, Clinical Outcome, and Quality of Life

Purpose: To evaluate the dosimetric superiority, efficacy, toxicity, and quality of life (QOL) data of intensity modulated radiation therapy (IMRT) in patients with primary gastric diffuse large B-cell lymphoma (PG-DLBCL). Methods and Materials: Forty-six consecutive patients with early-stage PG-DLBCL underwent IMRT after chemotherapy. The majority of patients (61.5%) were subclassified as the non-germinal center B cell–like subtype. Dosimetric parameters of the planning target volume (PTV) and organs at risk were assessed. Survival rates were depicted with the Kaplan-Meier method and compared with the log-rank test. Quality of life was evaluated using the QLQ-C30-STO22 questionnaires at the last follow-up contact. Results: The median PTV mean dose was 41.6 Gy. Only 0.73% of the PTV received <95% of the prescribed dose, indicating excellent target coverage. The median kidney V20 and liver V30 were 14.1% and 16.1%, respectively. The 5-year overall survival (OS), progression-free survival, and locoregional control rates for all patients were 80.4%, 75.0%, and 93.2%, respectively. Stage, lactate dehydrogenase level, and immunophenotype were significant prognostic factors for OS, and only stage was a significant factor for locoregional control. Consolidation IMRT in patients with complete response after chemotherapy resulted in significantly better OS and progression-free survival than salvage IMRT in patients with non-complete response. Two of 8 patients who had chronic liver disease experienced grade 4 or grade 5 acute hepatic failure after 4 to 5 cycles of rituximab-based chemotherapy and IMRT (40 Gy). No other serious acute or late toxicity was observed. The long-term global and functional QOL scales were excellent, with negligible symptom scales. Conclusions: Intensity modulated radiation therapy yielded excellent target coverage and critical tissue sparing and achieved favorable outcomes with acceptable toxicity and good long-term QOL in early-stage PG-DLBCL.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

Advancements in Development and Testing of Thermal Power Dispatch Simulators

Flexible plant operations and generation (FPOG) offer nuclear power plants (NPPs) the chance to leverage alternative, non-electric revenue streams while ensuring their continued role as reliable, clean, and constant sources of baseload electrical power. The excess thermal energy generated from NPPs during periods of low electricity demand can be channeled as raw materials to numerous industrial processes via a thermal power dispatch (TPD) system. Hydrogen production via high-temperature steam electrolysis (HTSE) is an optimal use case based on technical and economic feasibility. Researchers at Idaho National Laboratory (INL) have conducted previous works that developed and implemented TPD system models within the GSE Solutions Generic Pressurized Water Reactor (GPWR) simulator to support human-in-the-loop (HITL) scenario-based evaluations. The first part of this report documents modifications made to the GPWR TPD model and HMI from the previous iteration in line with a new Sargent and Lundy (S&L) TPD design with an automatic control system. The was done in collaboration with Westinghouse using their three-loop pressurizer water reactor (W3LPWR) simulator which contains an industrial grade automatic control system for the TPD. This was installed in the Human Systems Simulation Laboratory (HSSL) at INL. The second part of the report documents findings from an all-hands-on-deck integration and verification workshop that was conducted in the HSSL over several days. The research team comprised INL human factors and TPD experts, a nuclear engineer from GSE Solutions who implemented the revised TPD model for GPWR, the human-machine interface (HMI) prototyping and human factors team from the University of Idaho, and personnel with operations experience with pressurized water reactors. The workshop provided time and expertise to conduct the final activities to bring the operations, HMI, and simulator into a functional state. The goals of the integration and verification workshop were: 1. to install the revised GPWR TPD model into the HSSL 2. verify the TPD HMI prototype was functional 3. integrate the HTSE Simulink model to GPWR. 3. Issues were identified for resolution, but overall the workshop accomplished its goal to integrated and verify the majority of the intended functional. Future work will resolve the identified issues and use the integrated simulation to support an evaluation and demonstration in the next fiscal year.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2016

WIPP Certification of the Retrieval Box Assay System at the Advanced Mixed Waste Treatment Plant, Idaho - 16241

The Retrieval Box Assay System (RBAS) at the Advanced Mixed Waste Treatment Plant (AMWTP) is an Imaging Passive Active Neutron system supplemented with a High Purity Germanium (HPGe) gamma system for the quantification of Pu-239 Fissile Gram Equivalent (FGE) and transuranic (TRU) alpha activity of waste containers of various sizes up to 249 cm x 149 cm x 198 cm (Length x Width x Height). The system was originally calibrated in 2002 (with a range of surrogate matrices and radioactive sources in a 213 cm x 122 cm x 122 cm FRP box) and has been operational for over a decade. As of August 2015, the RBAS has measured approximately 18,000 boxes (50,000 m3 of waste) which has subsequently been fed into the facility's treatment process. Its success, and the wide envelope of waste that it can characterize, has led AMWTP to extend the RBAS mission to include WIPP certification. As part of this new project, the instrument must be capable of meeting WIPP's Waste Acceptance Criteria (WAC) which include reporting activities and masses of the 10 WIPP-tracked radionuclides. The system will be required to assay sludge and debris waste streams, shredded waste and large metal items. The container size includes Standard Waste Box (SWBs), Fiberglass Reinforced Plywood (FRPs) and large Shredder Boxes. Sludge matrices will be loaded into 210-liter (55-gallon) drums and placed inside an SWB. After assay, boxes will be over-packed into SLB-II's for shipment to WIPP. The target waste streams will contain mixtures of Weapons Grade plutonium, Heat Source plutonium (high in Pu-238 content) and Mixed Oxide (MOX). The activity of the waste is expected to encompass a wide dynamic range of activity from low-level waste (LLW) to TRU with up to several hundred grams of plutonium. Some packages will have high gamma activity associated with fission and activation products such as Cs-137 and Co-60. The existing RBAS hardware (detectors, electronics, assay chamber etc.) was retained for this project. Two lead filters were provided and installed on the existing filter wheels to attenuate the gamma ray flux from the highest activity boxes to avoid overload of the HPGe detectors. The new software suite includes PC-FRAM (Version 5), which is used for the isotopic analysis of the gamma spectra. Integration of FRAM and neutron results is performed using a software package known as RBAS WIPP Analysis Reporting Software (RWARS). This package also performs matrix dependent background adjustments. Other upgrades provided include automated tests that identify when assay parameters fall outside a predetermined range and a new Quality Checking (QC) application. Minimum Detectable Activity (MDA) values were determined for the active and passive neutron modes as a function of measured matrix correction indices. The resulting Minimum Detectable Concentration (MDC) has been demonstrated to be less than 3700 Bq/g alpha activity (100 nCi/g). Modifications were performed to update the system TMU parameters to accommodate assay of non-standard size boxes and a wider range of matrix materials. A series of calibration confirmation, measurements were performed on site in 2014 using a representative range of surrogate boxes and radioactive sources including Pu. The WIPP WAC performance criteria were successfully demonstrated up to 157 g Pu and the system passed its first Performance Demonstration Program (PDP) cycle in the Spring of 2015. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Synthetic Band Structure Engineering of Graphene Using Block Copolymer-Templated Dielectric Superlattices

Engineering the electronic band structure of two-dimensional (2D) materials by imposing spatially periodic superlattice (SL) potentials opens a pathway to unconventional electronics. Nanopatterning the gate electrode or surface dielectric near 2D crystals provides a powerful strategy for realizing electrostatically tunable “remote” SLs with flexibility in lattice design. Here, we demonstrate the effectiveness of block copolymer (BCP)-templated dielectric nanopatterns for fabricating etch-free high-grade metal oxide SLs. Alumina (AlO x ) nanopatterns with hexagonal symmetry and a 38 nm SL wavelength are produced as a model material by directly converting a self-assembled BCP film via block-selective vapor phase infiltration. Despite micrometer-scale rotational disorder inherent to BCP self-assembly, electronic transport measurements of graphene reveal replica Dirac points at zero field and Hofstadter mini-gaps under finite magnetic fields. These results indicate the successful formation of remote SL potentials in graphene resulting from optimized AlO x nanopattern fabrication to achieve consistent lattice symmetry and periodicity at a macroscopic scale. The findings of this study, combined with the versatile, scalable, and cost-effective nature of BCP nanopatterning, highlight the potential of BCP-templated nanostructures for remote SL engineering in 2D crystals.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Extended Sleeve Products Allow Control and Monitoring of Process Fluid Flows Inside Shielding, Behind Walls and Beneath Floors - 13041

Throughout power generation, delivery and waste remediation, the ability to control process streams in difficult or impossible locations becomes increasingly necessary as the complexity of processes increases. Example applications include radioactive environments, inside concrete installations, buried in dirt, or inside a shielded or insulated pipe. In these situations, it is necessary to implement innovative solutions to tackle such issues as valve maintenance, valve control from remote locations, equipment cleaning in hazardous environments, and flow stream analysis. The Extended Sleeve family of products provides a scalable solution to tackle some of the most challenging applications in hazardous environments which require flow stream control and monitoring. The Extended Sleeve family of products is defined in three groups: Extended Sleeve (ESV), Extended Bonnet (EBV) and Instrument Enclosure (IE). Each of the products provides a variation on the same requirements: to provide access to the internals of a valve, or to monitor the fluid passing through the pipeline through shielding around the process pipe. The shielding can be as simple as a grout filled pipe covering a process pipe or as complex as a concrete deck protecting a room in which the valves and pipes pass through at varying elevations. Extended Sleeves are available between roughly 30 inches and 18 feet of distance between the pipeline centerline and the top of the surface to which it mounts. The Extended Sleeve provides features such as ± 1.5 inches of adjustment between the pipeline and deck location, internal flush capabilities, automatic alignment of the internal components during assembly and integrated actuator mounting pads. The Extended Bonnet is a shorter fixed height version of the Extended Sleeve which has a removable deck flange to facilitate installation through walls, and is delivered fully assembled. The Instrument Enclosure utilizes many of the same components as an Extended Sleeve, yet allows the installation of process monitoring instruments, such as a turbidity meter to be placed in the flow stream. The basis of the design is a valve body, which, rather than having a directly mounted bonnet has lengths of concentric pipe added, which move the bonnet away from the valve body. The pipe is conceptually similar to an oil field well, with the various strings of casing, and tubing installed. Each concentric pipe provides a required function, such as the outermost pipes, the valve sleeve and penetration sleeve, which provide structural support to the deck flange. For plug valve based designs, the next inner pipe provides compression on the environmental seals at the top of the body to bonnet joint, followed by the innermost pipe which provides rotation of the plug, in the same manner as an extended stem. Ball valve ESVs have an additional pipe to provide compressive loading on the stem packing. Due to the availability of standard pipe grades and weights, the product can be configured to fit a wide array of valve sizes, and application lengths, with current designs as short as seven inches and as tall as 18 feet. Central to the design is the requirement for no special tools or downhole tools to remove parts or configure the product. Off the shelf wrenches, sockets or other hand tools are all that is required. Compared to other products historically available, this design offers a lightweight option, which, while not as rigidly stiff, can deflect compliantly under extreme seismic loading, rather than break. Application conditions vary widely, as the base product is 316 and 304 stainless steel, but utilizes 17-4PH, and other allows as needed based on the temperature range and mechanical requirements. Existing designs are installed in applications as hot as 1400 deg. F, at low pressure, and separately in highly radioactive environments. The selection of plug versus ball valve, metal versus soft seats, and the material of the seals and seats is all dependent on the application requirements. The design of the Extended Sleeve family of products provides a platform which solves a variety of accessibility problems associated with controlling process flow streams in remote, hard to reach locations in harsh environments. Installation of the equipment described has shown to allow access to flow streams that otherwise would require exceptional means to access and control. The Extended Sleeve family of products provides a scalable solution to both control and monitor process fluid flow through shielding, walls or floors when direct connection is advantageous. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Growth of Cd 0.9 Zn 0.1 Te 1-y Se y Single Crystals for Room Temperature Gamma-Ray Detection

Quaternary Cd 0.9 Zn 0.1 Te 1-y Sey (CZTS) single crystals, a novel room-temperature nuclear radiation detector semiconductor material, have been grown using a modified vertical Bridgman method (VBM) and a travelling heater method (THM). The percentage concentration of selenium in the VBM-grown crystal was 3% and that in the THM-grown crystal was 2%. While the THM Frisch collar detector (4.4 × 4.4 × 10.7 mm 3 ) produced a highly resolved pulse height spectra (PHS) with a resolution of ~1.06% for 662-keV gamma rays without any correction, the VBM-grown detector (10 × 10 × 2 mm 3 ) offered a high energy resolution of ~2% after application of a digital biparametric correction. The high-resolution performance of these detectors has been attributed to the addition of Se in the Cd 0.9 Zn 0.1 Te (CZT) matrix. Ab-initio calculations based on density functional theory (DFT) also confirmed that the addition of Se in the CZT matrix helps to reduce the formation of TeCd and the TeZn anti-sites. The VBM-grown crystals were characterized using powder x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS). While XRD results revealed sharp diffraction peaks confirming the crystalline nature of the grown crystal, the EDS results confirmed the targeted stoichiometry of the elemental composition. The bulk resistivity of the grown crystal was calculated to be ~3 × 10 10 Ω-cm from current-voltage characteristics recorded at room temperature in a planar configuration, ensuring that the grown CZTS crystals have low dark current as required for detector-grade crystals.

42 ENGINEERING↗
DOE OSTI2018

Microstructure and functionality of a uniquely graded super duplex stainless steel designed by a novel arc heat treatment method

Highlights: • A uniquely graded duplex stainless steel microstructure was fully characterized. • Nitrogen depletion occurred by solid state diffusion next to the fusion boundary. • Phase fractions and stability were compared to thermodynamic calculations. • Orientation relationships and morphology of sigma, chi, nitrides and R were studied. • A diagram summarizing functionality of aged duplex microstructures is introduced. - Abstract: A novel arc heat treatment technique was applied to design a uniquely graded super duplex stainless steel (SDSS), by subjecting a single sample to a steady state temperature gradient for 10 h. A new experimental approach was used to map precipitation in microstructure, covering aging temperatures of up to 1430 °C. The microstructure was characterized and functionality was evaluated via hardness mapping. Nitrogen depletion adjacent to the fusion boundary depressed the upper temperature limit for austenite formation and influenced the phase balance above 980 °C. Austenite/ferrite boundaries deviating from Kurdjumov–Sachs orientation relationship (OR) were preferred locations for precipitation of σ at 630–1000 °C, χ at 560–1000 °C, Cr{sub 2}N at 600–900 °C and R between 550 °C and 700 °C. Precipitate morphology changed with decreasing temperature; from blocky to coral-shaped for σ, from discrete blocky to elongated particles for χ, and from polygonal to disc-shaped for R. Thermodynamic calculations of phase equilibria largely agreed with observations above 750 °C when considering nitrogen loss. Formation of intermetallic phases and 475 °C-embrittlement resulted in increased hardness. A schematic diagram, correlating information about phase contents, morphologies and hardness, as a function of exposure temperature, is introduced for evaluation of functionality of microstructures.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Long-term Survival and Toxicity in Patients Treated With High-Dose Intensity Modulated Radiation Therapy for Localized Prostate Cancer

Purpose: To report long-term survival and toxicity outcomes with the use of high-dose intensity modulated radiation therapy (IMRT) to 86.4 Gy for patients with localized prostate cancer. Methods and Materials: Between August 1997 and December 2008, 1002 patients were treated to a dose of 86.4 Gy using a 5-7 field IMRT technique. Patients were stratified by prognostic risk group based on National Comprehensive Cancer Network risk classification criteria. A total of 587 patients (59%) were treated with neoadjuvant and concurrent androgen deprivation therapy. The median follow-up for the entire cohort was 5.5 years (range, 1-14 years). Results: For low-, intermediate-, and high-risk groups, 7-year biochemical relapse-free survival outcomes were 98.8%, 85.6%, and 67.9%, respectively (P<.001), and distant metastasis-free survival rates were 99.4%, 94.1%, and 82.0% (P<.001), respectively. On multivariate analysis, T stage (P<.001), Gleason score (P<.001), and >50% of initial biopsy positive core (P=.001) were predictive for distant mestastases. No prostate cancer-related deaths were observed in the low-risk group. The 7-year prostate cancer-specific mortality (PCSM) rates, using competing risk analysis for intermediate- and high-risk groups, were 3.3% and 8.1%, respectively (P=.008). On multivariate analysis, Gleason score (P=.004), percentage of biopsy core positivity (P=.003), and T-stage (P=.033) were predictive for PCSM. Actuarial 7-year grade 2 or higher late gastrointestinal and genitourinary toxicities were 4.4% and 21.1%, respectively. Late grade 3 gastrointestinal and genitourinary toxicity was experienced by 7 patients (0.7%) and 22 patients (2.2%), respectively. Of the 427 men with full potency at baseline, 317 men (74%) retained sexual function at time of last follow-up. Conclusions: This study represents the largest cohort of patients treated with high-dose radiation to 86.4 Gy, using IMRT for localized prostate cancer, with the longest follow-up to date. Our findings indicate that this treatment results in excellent clinical outcomes with acceptable toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2024

Development of an Optical Library for Coevaporated CdSe x Te 1– x

The conversion efficiency of CdTe solar cells may be improved by bandgap engineering, i.e., changing the bandgap value through the addition of Se in the absorber. The Se alloying enables a short-circuit current density improvement, as it leads to a bandgap energy value decrease. Furthermore, it has been associated with increased minority carrier lifetimes, assuring high open-circuit voltage values. An Se gradient profile control can further optimize the solar cell performance. Thus, an optical model baseline of the CdSe x Te 1–x (CST) compound was developed. Spectroscopic ellipsometry measurements were conducted to accurately extract the optical constants of ten CST layers deposited through coevaporation with x varying from 0 to 1. Using the measured dielectric function spectra from the discrete CST layers with varying x, and considering the composition-induced shift in the critical point energies, an energy-shift model was employed to develop the accurate optical library for the CST compound for any x value to provide data for future modeling and optimization. Furthermore, the library accuracy was validated through optical simulations of the quantum efficiency of a graded CST solar cell using the finite-difference time-domain method by replicating the Se profile in the absorber layer measured through secondary ion mass spectrometry.

14 SOLAR ENERGY↗
DOE OSTI2016

Computed Tomography–Planned High-Dose-Rate Brachytherapy for Treating Uterine Cervical Cancer

Purpose: To evaluate the long-term results of computed tomography (CT)–planned high-dose-rate (HDR) brachytherapy (BT) for treating cervical cancer patients. Methods and Materials: CT-planned HDR BT was performed according to the adapted Group European de Curietherapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) recommendations in 216 consecutive patients with locally advanced cervical cancer, International Federation of Gynecology and Obstetrics (FIGO) stage IB to IVA, who were treated with conformal external beam radiation therapy and concomitant chemotherapy. We analyzed outcomes and late side effects evaluated according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer and Subjective, Objective, Management, Analysis evaluation scoring system and compared them with the results from a historical group. Results: The median age was 56 years (range, 32-83 years). The median follow-up time for living patients was 52 months (range 37-63 months). The 5-year cumulative incidence function for the local recurrence rate for patients with FIGO II and III was 5.5% and 20%, respectively (P=.001). The 5-year rates of overall survival (OS) and disease-free survival (DFS) were 66.4% and 58.5%, respectively. The relative risk of failure for OS and DFS for FIGO III in relation to FIGO II was 2.24 (P=.003) and 2.6 (P=.000) and for lymph node enlargement was 2.3 (P=.002) and 2 (P=.006), respectively. In 2 patients, rectovaginal fistula occurred, and in 1 patient, vesicovaginal fistula occurred without local progression. Comparison of late adverse effects in patients treated according to the GEC-ESTRO recommendations and in the historical group revealed a reduction in fistula formation of 59% and also a reduction in rectal grade 3 to 4 late toxicity of >59%. Conclusions: This is the largest report with mature data of CT-planned BT HDR for the treatment of cervical cancer with good local control and acceptable toxicity. In comparison with the historical series, there is a substantial benefit in terms of severe late effects. FIGO III and enlarged lymph nodes in positron emission tomography–CT/CT are negative prognostic factors, both with a relative risk of failure of approximately 2.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

AHTR Mechanical, Structural, and Neutronic Preconceptual Design

This report provides an overview of the mechanical, structural, and neutronic aspects of the Advanced High Temperature Reactor (AHTR) design concept. The AHTR is a design concept for a large output Fluoride salt cooled High-temperature Reactor (FHR) that is being developed to enable evaluation of the technology hurdles remaining to be overcome prior to FHRs becoming an option for commercial reactor deployment. This report documents the incremental AHTR design maturation performed over the past year and is focused on advancing the design concept to a level of a functional, self-consistent system. The reactor concept development remains at a preconceptual level of maturity. While the overall appearance of an AHTR design is anticipated to be similar to the current concept, optimized dimensions will differ from those presented here. The AHTR employs plate type coated particle fuel assemblies with rapid, off-line refueling. Neutronic analysis of the core has confirmed the viability of a 6-month two-batch cycle with 9 wt. % enriched uranium fuel. Refueling is intended to be performed automatically under visual guidance using dedicated robotic manipulators. The report includes a preconceptual design of the manipulators, the fuel transfer system, and the used fuel storage system. The present design intent is for used fuel to be stored inside of containment for at least six months and then transferred to local dry wells for intermediate term, on-site storage. The mechanical and structural concept development effort has included an emphasis on transportation and constructability to minimize construction costs and schedule. The design intent is that all components be factory fabricated into rail transportable modules that are assembled into subsystems at an on-site workshop prior to being lifted into position using a heavy-lift crane in an open-top style construction. While detailed accident identification and response sequence analysis has yet to be performed, the design concept incorporates fully passive responses to all identified design basis or non-very-low frequency beyond design basis accidents as well as multiple levels of radioactive material containment. Key building design elements include (1) below grade siting to minimize vulnerability to aircraft impact, (2) multiple natural circulation decay heat rejection chimneys, (3) seismic base isolation, and (4) decay heat powered back-up electricity generation.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2014

Prospective Evaluation of Acute Toxicity and Quality of Life After IMRT and Concurrent Chemotherapy for Anal Canal and Perianal Cancer

Purpose: A prospective cohort study was conducted to evaluate toxicity, quality of life (QOL), and clinical outcomes in patients treated with intensity modulated radiation therapy (IMRT) and concurrent chemotherapy for anal and perianal cancer. Methods and Materials: From June 2008 to November 2010, patients with anal or perianal cancer treated with IMRT were eligible. Radiation dose was 27 Gy in 15 fractions to 36 Gy in 20 fractions for elective targets and 45 Gy in 25 fractions to 63 Gy in 35 fractions for gross targets using standardized, institutional guidelines, with no planned treatment breaks. The chemotherapy regimen was 5-fluorouracil and mitomycin C. Toxicity was graded with the National Cancer Institute Common Terminology Criteria for Adverse Events, version 3. QOL was assessed with the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and CR29 questionnaires. Correlations between dosimetric parameters and both physician-graded toxicities and patient-reported outcomes were evaluated by polyserial correlation. Results: Fifty-eight patients were enrolled. The median follow-up time was 34 months; the median age was 56 years; 52% of patients were female; and 19% were human immunodeficiency virus—positive. Stage I, II, III, and IV disease was found in 9%, 57%, 26%, and 9% of patients, respectively. Twenty-six patients (45%) required a treatment break because of acute toxicity, mainly dermatitis (23/26). Acute grade 3 + toxicities included skin 46%, hematologic 38%, gastrointestinal 9%, and genitourinary 0. The 2-year overall survival (OS), disease-free survival (DFS), colostomy-free survival (CFS), and cumulative locoregional failure (LRF) rates were 90%, 77%, 84%, and 16%, respectively. The global QOL/health status, skin, defecation, and pain scores were significantly worse at the end of treatment than at baseline, but they returned to baseline 3 months after treatment. Social functioning and appetite scores were significantly better at 12 months than at baseline. Multiple dose-volume parameters correlated moderately with diarrhea, skin, and hematologic toxicity scores. Conclusion: IMRT reduces acute grade 3 + hematologic and gastrointestinal toxicities compared with reports from non-IMRT series, without compromising locoregional control. The reported QOL scores most relevant to acute toxicities returned to baseline by 3 months after treatment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗