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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

The Impact of Radiotherapy on Reoperation Rates in Patients Undergoing Mastectomy and Breast Reconstruction

Objective: The aim of this study was to determine the impact of postmastectomy radiotherapy (PMRT) on reoperation rates in women with breast cancer undergoing mastectomy and breast reconstruction. Methods: Between June 2001 and December 2015, 832 breast cancer patients treated with mastectomy and breast reconstruction with (n = 159) or without (n = 673) PMRT were analyzed retrospectively. Reoperations following breast reconstruction were categorized into the following three types: anticipated, unanticipated, and others. Multivariable logistic regression models were used to evaluate the impact of PMRT on overall and unanticipated reoperations according to different breast reconstruction types after adjusting for relevant covariates. Results: With a median follow-up of 58.5 months, a total of 1298 operations were performed in 832 breast cancer patients. The rates of overall and unanticipated reoperations were 46.2% and 7.7%, respectively. Multivariable analysis showed that PMRT was not associated with overall reoperations in either implant-based reconstruction patients (odds ratio [OR] 1.00, 95% confidence interval [CI] 0.43–2.37, p = 0.995) or autologous reconstruction patients (OR 0.85, 95% CI 0.52–1.40, p = 0.533); however, the impact of PMRT on unanticipated reoperations differed by reconstruction type. In patients who received implant-based reconstructions, PMRT was associated with a 3.05-fold (95% CI 1.20–7.75, p = 0.019) higher odds of unanticipated reoperations, while there was no difference in patients who underwent autologous reconstruction (OR 1.17, 95% CI 0.51–2.66, p = 0.713). Delayed reconstruction or delayed–immediate reconstructions were associated with an increased risk of both overall and unanticipated reoperations in both reconstruction cohorts. Conclusions: PMRT appears to be associated with an increased risk of unanticipated reoperations among patients receiving implant-based reconstruction, but not among those receiving autologous reconstruction. The risk of reoperation should be taken into consideration when selecting the appropriate breast reconstruction type when PMRT is planned.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Radiation Therapy After Breast-Conserving Surgery in Women 70 Years of Age and Older: How Wisely Do We Choose?

Background: Despite data from randomized trials supporting omission of radiation therapy (RT) for women ≥ 70 years of age with T1, estrogen receptor-positive (ER+) tumors undergoing breast-conserving therapy (BCT), RT usage remains high. We reviewed our institutional experience to determine if risk factors for local recurrence or comorbidities influenced use. Methods: Women ≥ 70 years of age with T1, ER+, human epidermal growth factor receptor 2-negative (HER2−) tumors undergoing BCT in 2010–2012 were identified from a prospectively maintained database. Ten-year estimated mortality was calculated using the Suemoto index. The associations of clinicopathological features and mortality risk on receipt of RT were examined. Results: Overall, 323 patients with 327 cancers were identified. Median age was 75 years, median tumor size was 1 cm, and all were clinically node negative; 53.7% of patients received RT. RT usage decreased with age (73.6%, age 70–74 years; 49.5%, age 75–79 years; 33.3%, age 80–84 years; 10.7%, ≥ 85 years; p < 0.001). Within age groups, estimated mortality did not impact RT usage. On multivariable analysis, only younger age and larger tumor size were associated with RT use. Recurrence-free survival was 98% versus 93% with and without RT, respectively (p = 0.011). Those who received adjuvant radiation also had improved overall survival (92% vs. 89%), although this effect did not reach statistical significance (p = 0.051). Conclusion: Neither the factors associated with risk of local recurrence nor the estimated risk of death in 10 years were associated with use of adjuvant radiation in a large cohort of women ≥ 70 years of age with small ER+ breast cancers treated with breast-conserving surgery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Completion Lymph Node Dissection or Radiation Therapy for Sentinel Node Metastasis in Merkel Cell Carcinoma

Background: For sentinel lymph node (SLN) metastasis from Merkel cell carcinoma (MCC), the benefit of completion lymph node dissection (CLND) versus radiation therapy (RT) is unclear. This study compares outcomes for patients with SLN metastasis undergoing CLND or RT. We also evaluated positive non-SLNs as a prognostic factor. Methods: Using a prospective database, we identified MCC patients with SLN metastasis who underwent CLND or RT. At our institution, CLND was recommended for patients with acceptable perioperative risk, while therapeutic RT was offered to those with high perioperative risk. Primary outcomes were MCC-specific survival (MCCSS), disease-free survival (DFS), nodal recurrence-free survival (NRFS), and distant recurrence-free survival (DRFS). Results: From 2006 to 2017, 163 patients underwent CLND (n = 137) or RT (n = 26). Median follow-up was 1.9 years. CLND had no significant differences for MCCSS (5-year survival 71% vs. 64%, p = 1.0), DFS (52% vs. 61%, p = 0.8), NRFS (76% vs. 91%, p = 0.3), or DRFS (65% vs. 75%, p = 0.3) compared with RT. Patients with positive non-SLNs (n = 44) had significantly worse MCCSS (5-year survival 39% vs. 87%, p < 0.001), DFS (35% vs. 60%, p = 0.005), and DRFS (54% vs. 71%, p = 0.03) compared with negative non-SLNs (n = 93). Multivariate analysis showed positive non-SLNs were independently associated with MCCSS, DFS, and DRFS. Conclusions: CLND and RT may have similar outcomes for MCC patients with SLN metastasis when treatment aligns with our institutional practices. For patients undergoing CLND, positive non-SLNs is an important prognostic factor associated with poor survival and distant recurrence. This high-risk group should be considered for adjuvant systemic therapy trials.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Elective Paratracheal Lymph Node Dissection in Salvage Laryngectomy

Background: Indications for and efficacy of paratracheal nodal dissection (PTND) in patients undergoing laryngectomy (salvage) for persistent or recurrent laryngeal squamous cell carcinoma are not well-defined. Methods: A retrospective cohort study was performed for patients undergoing salvage laryngectomy with clinically and radiographically negative neck disease between 1998 and 2015 (n = 210). Univariate and multivariate Cox regression analyses were performed. Results: PTND was performed on 77/210 patients (36%). The PTND cohort had a greater proportion of advanced T classification (rT3/rT4) tumors (78%) than subjects without PTND (55%; p = 0.001). There was a 14% rate of occult nodal metastases in the paratracheal basin; of these, 55% did not have pathologic lateral neck disease. Multivariate analysis controlling for tumor site, tumor stage, and pathologic lateral neck disease demonstrated that PTND was associated with improved overall survival [OS] (p = 0.03; hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.38–0.96), disease-free survival [DFS] (p = 0.03; HR 0.55, 95% CI 0.31–0.96), and distant DFS survival (p = 0.01; HR 0.29, 95% CI 0.11–0.77). The rate of hypocalcemia did not differ between subjects who underwent bilateral PTND, unilateral PTND, or no PTND (p = 0.19 at discharge, p = 0.17 at last follow-up). Conclusions: PTND at the time of salvage laryngectomy was more common in patients with rT3/rT4 tumors and was associated with improved OS and DFS, with no effect on hypocalcemia. In patients undergoing PTND, the finding of occult paratracheal metastases was often independent of lateral neck metastases.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Significance of Metabolic Tumor Volume at Baseline and Reduction of Mean Standardized Uptake Value in {sup 18}F-FDG-PET/CT Imaging for Predicting Pathological Complete Response in Breast Cancers Treated with Preoperative Chemotherapy

Background: The usefulness of {sup 18}F-fluorodeoxyglucose-positron emission tomography/computed tomography for evaluating the treatment efficacy of breast cancers is well-established; however, the predictive values of parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) remain unknown. Methods: This study examined 199 breast cancers treated with primary systemic chemotherapy (PSC) followed by operation, and determined the values of maximum standardized uptake value (SUV{sub max}), peak SUV (SUV{sub peak}), mean SUV (SUV{sub mean}), MTV, and TLG at baseline. Among these cases, data on early changes in these metabolic parameters in 70 breast cancers were also assessed. Results: A pathological complete response (pCR) was achieved in 64 breast cancers. Breast cancers with low MTV at baseline had a significantly higher pCR rate than breast cancers with high MTV (47.9% vs. 23.4%; p = 0.0005). High reduction rates (∆) of SUV{sub max} (p = 0.0001), SUV{sub peak} (p = 0.0001), and SUV{sub mean} (p < 0.0001) resulted in an increased pCR compared with those for low ∆. The pCR rate was highest for the combination of low MTV and high ∆SUV{sub mean} (86.7%), and lowest for high MTV and low ∆SUV{sub mean} (15.4%); the remaining combinations were intermediate (58.6%; p < 0.0001). The combination of low MTV at baseline and high ∆SUV{sub mean} was a significant and independent predictor for pCR (odds ratio 28.63; 95% confidence interval 1.94–422.42; p = 0.0146) in multivariable analysis. Conclusions: Low levels of MTV at baseline and a high reduction of SUV{sub mean} after PSC was significantly associated with pCR. These findings suggest the usefulness of these metabolic parameters for predicting the treatment efficacy of breast cancers.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Treatment-Related Lymphopenia Predicts Pathologic Complete Response and Recurrence in Esophageal Squamous Cell Carcinoma Undergoing Neoadjuvant Chemoradiotherapy

Purpose: To investigate the relationship between treatment-related lymphopenia and pathologic response to neoadjuvant chemoradiotherapy (CRT) in patients with esophageal squamous cell carcinoma (ESCC). Methods: Between 2002 and 2016, 220 ESCC patients treated with neoadjuvant CRT followed by surgery were retrospectively analyzed. Absolute lymphocyte count was determined before, during, and 1 month after neoadjuvant CRT. Treatment-related lymphopenia was graded using Common Terminology Criteria for Adverse Events version 4.0. Relationship between lymphopenia with pathologic complete response (pCR) and recurrence were evaluated. Results: Ninety-five patients (43.2%) achieved a pCR after neoadjuvant CRT and 71 patients (32.3%) developed recurrences. The incidence of grade 0, 1, 2, 3, and 4 lymphopenia during CRT were 1.8%, 6.8%, 31.4%, 38.2% and 21.8%, respectively. Patients with grade 4 lymphopenia had a significantly lower pCR rate than those with grade 0-3 lymphopenia (22.9% vs. 48.8%, P = 0.001). Moreover, grade 4 lymphopenia was significantly associated with a higher risk of recurrences (45.8% vs. 28.5%, P = 0.023). Multivariable analysis identified that primary tumor length, tumor location, and radiation dose were independent predictors for grade 4 lymphopenia. Conclusions: ESCC patients with grade 4 lymphopenia during neoadjuvant CRT were associated with a significantly lower pCR rate and a higher recurrence risk.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Cholangiographic Tumor Classification for Simple Patient Selection Prior to Hepatopancreatoduodenectomy for Cholangiocarcinoma

Background: Hepatopancreatoduodenectomy (HPD) is employed for patients with laterally advanced cholangiocarcinoma. However, the survival benefit of this extended approach remains controversial. The aim of this study is to identify a tumor feature benefiting from HPD from the standpoint of long-term survival. Patients and Methods: Patients with cholangiocarcinoma who underwent HPD with curative intent between 2001 and 2017 were retrospectively analyzed. Tumors were radiologically classified by preoperative cholangiogram. Diffuse type was defined as significant tumor/stricture located from the hilar to intrapancreatic duct; localized type was defined as tumor otherwise. Univariable and multivariable analyses were performed to identify prognostic indicators. Results: Of 100 study patients, 28 (28%) patients had diffuse tumor type, while the remaining 72 (72%) patients had localized tumors. The former group showed significantly longer lateral length (43 versus 22 mm, P < 0.001) and more frequent pancreatic invasion (50% versus 32%, P = 0.110), advanced T classification (64% versus 49%, P = 0.185), and nodal metastasis (57% versus 47%, P = 0.504), compared with the latter group. The survival for patients with diffuse tumor type was significantly worse than that for patients with localized tumor type, with 5-year survival rates of 59.0% versus 26.3%, respectively (P = 0.003). Multivariable analysis identified four independent factors deteriorating long-term survival: cholangiographic diffuse tumor (P = 0.021), higher age (P = 0.020), percutaneous biliary drainage (P = 0.007), and portal vein resection (P = 0.007). Conclusions: Presurgical cholangiographic classification, diffuse or localized type, is a tumor-related factor closely associated with survival probability; therefore, it may be a useful feature for patient selection prior to HPD for cholangiocarcinoma.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Prognostic Role of the Immunoscore for Patients with Urothelial Carcinoma of the Bladder Who Underwent Radical Cystectomy

Background: Increasing evidence suggests that cancer progression is strongly influenced by the host immune response, which is represented by immune cell infiltrates. The T-lymphocyte-based Immunoscore is reported to be a reliable prognostic factor in colon cancer, but its significance in urothelial carcinoma of the bladder (UCB) is at an early stage of exploration. This study aimed to determine whether the tumor immune infiltrate, as evaluated by the Immunoscore, could act as a useful prognostic marker for UCB patients who have undergone radical cystectomy (RC). Methods: In this study, immunohistochemistry was used to examine the Immunoscore of 221 UCB patients who underwent RC. The Immunoscore of the patients was determined by the densities of CD3+ and CD8+ T cells at the tumor center and the invasive margin. Results: A highly significant association between a low Immunoscore and a shortened patient survival (P < 0.001, log-rank test) was demonstrated. In different subsets of UCB patients, a low Immunoscore also was a prognostic indicator of pT ≤ 2, pN(–)-status tumors, negative vascular invasion, or both (P < 0.05). Importantly, the Immunoscore together with the patient’s pT status provided significant independent prognostic parameters in the multivariate analysis (P < 0.05). Furthermore, a significant correlation (P = 0.003) of a low Immunoscore with an increased UCB labeling index of Ki-67 (a cell proliferation marker) was observed in this UCB cohort. Conclusions: The findings suggest that the Immunoscore, as examined by immunohistochemistry, might serve as a novel prognostic marker for UCB patients who have undergone RC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Physician Knowledge of Breast Cancer Recurrence and Contralateral Breast Cancer Risk is Associated with Increased Recommendations for Contralateral Prophylactic Mastectomy: a Survey of Physicians at NAPBC-Accredited Centers

Background: Physician recommendation for contralateral prophylactic mastectomy (CPM) has been shown to influence whether a patient chooses CPM. Few studies have explored physician knowledge about contralateral breast cancer (CBC) and local recurrence (LR) risk and whether knowledge is associated with recommendation for CPM. Methods: We conducted a cross-sectional survey of physicians at National Accreditation Program for Breast Centers-accredited breast centers across the USA. Physician knowledge levels of CBC and LR were assessed and correlated with recommendations for CPM. Results: A total of 2412 physicians were surveyed with a 51% response rate (n = 1226). The results showed that 66% had correct knowledge about CBC risk and 57% had correct knowledge about LR. Moreover, 634 had high knowledge, viz. 176 (55.4%) breast surgeons, 171 (58.0%) medical oncologists, 196 (62.0%) radiation oncologists, and 72 (29.9%) plastic surgeons (p < 0.01). Compared with high knowledge, low knowledge was associated with favoring insurance coverage for patients at average CBC risk (53.8% vs. 39.8%, p < 0.01). Low knowledge was also associated with feeling that CPM was indicated in patients with high recurrence anxiety (39.2% vs. 28.9%), young patients with estrogen receptor (ER)-negative cancer (25.3% vs. 18.5%), and patients with two first-degree relatives with breast cancer (40.0% vs. 32.3%) (all p < 0.01). Multivariable analysis found physician type [odds ratio (OR) 3.76 for surgeons] and low knowledge (OR 1.46) to be significant independent predictors of favoring insurance coverage for CPM in patients at average risk. Conclusions: Physician knowledge about CBC and LR could be improved. Lower knowledge is associated with favorable physician recommendations for CPM. It is not clear whether improving physician knowledge will change recommendations for CPM.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

National variability in Americans’ COVID-19 protective behaviors: Implications for vaccine roll-out

Protective behaviors such as mask wearing and physical distancing are critical to slow the spread of COVID-19, even in the context of vaccine scale-up. Understanding the variation in self-reported COVID-19 protective behaviors is critical to developing public health messaging. The purpose of the study is to provide nationally representative estimates of five self-reported COVID-19 protective behaviors and correlates of such behaviors. In this cross-sectional survey study of US adults, surveys were administered via internet and telephone. Adults were surveyed from April 30-May 4, 2020, a time of peaking COVID-19 incidence within the US. Participants were recruited from the probability-based AmeriSpeak® national panel. Brief surveys were completed by 994 adults, with 73.0% of respondents reported mask wearing, 82.7% reported physical distancing, 75.1% reported crowd avoidance, 89.8% reported increased hand-washing, and 7.7% reported having prior COVID-19 testing. Multivariate analysis (p critical value .05) indicates that women were more likely to report protective behaviors than men, as were those over age 60. Respondents who self-identified as having low incomes, histories of criminal justice involvement, and Republican Party affiliation, were less likely to report four protective behaviors, though Republicans and individuals with criminal justice histories were more likely to report having received COVID-19 testing. The majority of Americans engaged in COVID-19 protective behaviors, with low-income Americans, those with histories of criminal justice involvement, and self-identified Republicans less likely to engage in these preventive behaviors. Culturally competent public health messaging and interventions might focus on these latter groups to prevent future infections. These findings will remain highly relevant even with vaccines widely available, given the complementarities between vaccines and protective behaviors, as well as the many challenges in delivering vaccines.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Macroinvertebrate community responses to gravel augmentation in a high-gradient, Southeastern regulated river

Sediment transport, one of the key processes of river systems, is altered or stopped by dams, leaving lower river reaches barren of sand and gravel, both of which are essential habitat for fish and macroinvertebrates. One way to compensate for losses in sediment is to supplement gravel to river reaches below impoundments. Because gravel addition has become a widespread practice, it is essential to evaluate the biotic response to restoration projects in order to improve the efficacy of future applications. The purpose of our study was to evaluate the response of the macroinvertebrate community to gravel addition in a high-gradient, regulated river in western North Carolina. We collected benthic macroinvertebrate samples from gravel-enhanced areas and unenhanced areas for 1 season before gravel addition, and for 4 seasons afterwards. Repeated measures multivariate analysis of variance indicated that the responses of macroinvertebrates to gravel addition were generally specific to individual taxa or particular functional feeding groups and did not lead to consistent patterns in overall family richness, diversity, density, or evenness. Non-metric multi-dimensional scaling showed that shifts in macroinvertebrate community composition were temporary and dependent upon site conditions and season. Correlations between macroinvertebrate response variables and substrate microhabitat variables existed with or without the inclusion of data from enhanced areas, which suggests that substrate-biotic relationships were present before gravel addition. A review of the current literature suggests that the responses of benthic macroinvertebrates to substrate restoration are inconsistent and dependent upon site conditions and the degree habitat improvement of pre-restoration site conditions.

functional feeding group↗
DOE OSTI2015

Search for the electroweak production of supersymmetric particles in s =8 TeV p p collisions with the ATLAS detector

The ATLAS experiment has performed extensive searches for the electroweak production of charginos, neutralinos and staus. This article summarizes and extends the search for electroweak supersymmetry with new analyses targeting scenarios not covered by previously published searches. New searches use vector-boson fusion production, initial-state radiation jets, and low-momentum lepton final states, as well as multivariate analysis techniques to improve the sensitivity to scenarios with small mass splittings and low-production cross-sections.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Both the intratumoral immune and microbial microenvironment are linked to recurrence in human colon cancer: results from a prospective, multicenter nodal ultrastaging trial

Background: Colon cancer (CC) is the third most common cancer diagnosed in the United States and the incidence has been rising among young adults. We and others have shown a relationship between the immune infiltrate and prognosis, with improved disease-free survival (DFS) associated with a higher expression of CD8+ T cells. Additionally, numerous studies indicate the gut microbiota is linked to colon cancer and clinical outcomes. Therefore, we hypothesized a microbial signature might be associated with both the intratumoral immune cells as well as DFS. Results: Ninety-one patients were randomly selected from a prospective NCI-sponsored multicenter trial evaluating ultrastaging in CC to investigate the intratumoral microbiota by 16S rRNA gene amplicon sequencing. Operational taxonomic units (OTUs) were grouped by 97% sequence similarity. A series of clinical, immunohistochemical, and microbiota-related data were first evaluated by univariable cox regression to determine candidate variables associated with DFS. DFS was influenced by three parameters: N-stage, CD8+ labeling, and one microbiota principal component by multivariate analysis (MVA). Not only were the microbiota and CD8 significant contributors to the DFS model, but they were also significantly associated with each other. Alpha diversity showed an inverse correlation to CD8+ T cells (p=0.010, R=-0.278) and beta diversity showed an association with the CD8+ T cells (u-UniFrac p=0.026, w-UniFrac p=0.034). Further analysis at the OTU level with false discovery correction revealed one OTU, OTU_104, belonging to the order Clostridiales to be associated with increased recurrence (HR 1.21, CI 1.08 to 1.36). This OTU_104 was then found to be inversely correlated to CD8+ T cells (p=0.031, R=-0.35). Conclusions: This study is the first to demonstrate an association between the intratumoral microbiota, CD8+ T cells, and recurrence in CC. An increased relative abundance of a specific OTU_104 was inversely associated with CD8+ T cells and increased CC recurrence. The link between this microbe, CD8+ T cells and DFS has not been previously shown. Further studies are warranted to examine the role of infiltrating immune cells and the microbiota on colon cancer.

colon cancer↗
DOE OSTI2023

Association of Serum Bile Acid and Unsaturated Fatty Acid Profiles with the Risk of Diabetic Retinopathy in Type 2 Diabetic Patients

Aim: We aimed to identify the ability of serum bile acids (BAs) and unsaturated fatty acids (UFAs) profiles to predict the development of diabetic retinopathy (DR) in type 2 diabetes mellitus (T2DM) patients. Methods: We first used univariate and multivariate analysis to compare 15 serum BA and 11 UFA levels in healthy control (HC) group (n = 82), T2DM patients with DR (n = 58) and T2DM patients without DR (n = 60). Forty T2DM patients were considered for validation. Then, the receiver operating characteristic curve (ROC) and decision curve analysis were used to assess the diagnostic value and clinical benefit of serum biomarkers alone, clinical variables alone or in combination, and the area under the curve (AUC), integrated discrimination improvement (IDI), and net reclassification improvement (NRI) were used to further assess whether the addition of biomarkers significantly improved the predictive ability of the model. Results: Orthogonal partial least squares-discriminant analysis (OPLS-DA) of serum BAs and UFAs separated the three cohorts including HC, T2DM patients with or without DR. The difference in serum BA and UFA profiles of T2DM patients with or without DR was mainly manifested in the three metabolites of taurolithocholic acid (TLCA), tauroursodeoxycholic acid (TUDCA) and arachidonic acid (AA). Together, they had an AUC of 0.785 (0.918 for validation cohort) for predicting DR in T2DM patients. After adjusting for numerous confounding factors, TLCA, TUDCA, and AA were independent predictors that differentiated T2DM with or without DR. The results of AUC, IDI, and NRI demonstrated that adding these three biomarkers to a model with clinical variables statistically increased their predictive value and were replicated in our independent validation cohort. Conclusion: These findings highlight the association of three metabolites, TLCA, TUDCA and AA, with DR and may indicate their potential value in the pathogenesis of DR.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Plasmonics Based Harsh Environment Compatible Chemical Sensors

Au-YSZ, Au-TiO 2 and Au-CeO 2 nanocomposite films have been investigated as a potential sensing element for high-temperature plasmonic sensing of H 2 , CO, and NO 2 in an oxygen containing environment. The Au-YSZ and Au-TiO 2 films were deposited using PVD methods, while the CeO 2 thin film was deposited by molecular beam epitaxy (MBE) and Au was implanted into the as-grown film at an elevated temperature followed by high temperature annealing to form well-defined Au nanoclusters. Each of the films were characterized by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). For the gas sensing experiments, separate exposures to varying concentrations of H 2 , CO, and NO 2 were performed at a temperature of 500°C in oxygen backgrounds of 5.0, 10, and ~21% O 2 . Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidation-reduction processes that fill or create oxygen vacancies in the respective metal oxides. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles or by changes in the dielectric constant surrounding the particles. Hyperspectral multivariate analysis was used to gauge the inherent selectivity of the film between the separate analytes. From principal component analysis (PCA), unique and identifiable responses were seen for each of the analytes. Linear discriminant analysis (LDA) was also used on the Au-CeO 2 results and showed separation between analytes as well as trends in gas concentration. Results indicate that each of the films are is selective towards O 2 , H 2 , CO, and NO 2 in separate exposures. However, when the films were analyzed in a sensor array based experiment, ie simultaneous exposures to the target gases, PCA analysis of the combined response showed an even greater selective character towards the target gases. Combined with the observed stability over long exposure periods, each of these Au-metal oxide films shows good potential as an optical sensing element for harsh environmental conditions.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

Organic Aerosol Component (OACOMP) Value-Added Product (Report)

Significantly improved returns in their aerosol chemistry data can be achieved via the development of a value-added product (VAP) of deriving OA components, called Organic Aerosol Components (OACOMP). OACOMP is primarily based on multivariate analysis of the measured organic mass spectral matrix. The key outputs of OACOMP are the concentration time series and the mass spectra of OA factors that are associated with distinct sources, formation and evolution processes, and physicochemical properties.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Automated Characterization of Spent Fuel through the Multi-Isotope Process (MIP) Monitor

This research developed an algorithm for characterizing spent nuclear fuel (SNF) samples based on simulated gamma spectra. The gamma spectra for a variety of light water reactor fuels typical of those found in the United States were simulated. Fuel nuclide concentrations were simulated in ORIGEN-ARP for 1296 fuel samples with a variety of reactor designs, initial enrichments, burn ups, and cooling times. The results of the ORIGEN-ARP simulation were then input to SYNTH to simulate the gamma spectrum for each sample. These spectra were evaluated with partial least squares (PLS)-based multivariate analysis methods to characterize the fuel according to reactor type (pressurized or boiling water reactor), enrichment, burn up, and cooling time. Characterizing some of the features in series by using previously estimated features in the prediction greatly improves the performance. By first classifying the spent fuel reactor type and then using type-specific models, the prediction error for enrichment, burn up, and cooling time improved by a factor of two to four. For some features, the prediction was further improved by including additional information, such as including the predicted burn up in the estimation of cooling time. The optimal prediction flow was determined based on the simulated data. A PLS discriminate analysis model was developed which perfectly classified SNF reactor type. Burn up was predicted within 0.1% root mean squared percent error (RMSPE) and both cooling time and initial enrichment within approximately 2% RMSPE.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗