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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Radiation-Related New Primary Solid Cancers in the Childhood Cancer Survivor Study: Comparative Radiation Dose Response and Modification of Treatment Effects

Objectives: The majority of childhood cancer patients now achieve long-term survival, but the treatments that cured their malignancy often put them at risk of adverse health outcomes years later. New cancers are among the most serious of these late effects. The aims of this review are to compare and contrast radiation dose–response relationships for new solid cancers in a large cohort of childhood cancer survivors and to discuss interactions among treatment and host factors. Methods: This review is based on previously published site-specific analyses for subsequent primary cancers of the brain, breast, thyroid gland, bone and soft tissue, salivary glands, and skin among 12,268 5-year childhood cancer survivors in the Childhood Cancer Survivor Study. Analyses included tumor site–specific, individual radiation dose reconstruction based on radiation therapy records. Radiation-related second cancer risks were estimated using conditional logistic or Poisson regression models for excess relative risk (ERR). Results: Linear dose–response relationships over a wide range of radiation dose (0-50 Gy) were seen for all cancer sites except the thyroid gland. The steepest slopes occurred for sarcoma, meningioma, and nonmelanoma skin cancer (ERR/Gy > 1.00), with glioma and cancers of the breast and salivary glands forming a second group (ERR/Gy = 0.27-0.36). The relative risk for thyroid cancer increased up to 15-20 Gy and then decreased with increasing dose. The risk of thyroid cancer also was positively associated with chemotherapy, but the chemotherapy effect was not seen among those who also received very high doses of radiation to the thyroid. The excess risk of radiation-related breast cancer was sharply reduced among women who received 5 Gy or more to the ovaries. Conclusions: The results suggest that the effect of high-dose irradiation is consistent with a linear dose–response for most organs, but they also reveal important organ-specific and host-specific differences in susceptibility and interactions between different aspects of treatment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Modification of magnetic ground state in Tb 2 Ni 0.90 Si 2.94 by thermal annealing

In this work, we have investigated the thermal annealing effect on the physical properties of an AlB 2 -type ternary intermetallic compound, Tb 2 Ni 0.90 Si 2.94 , that undergoes spin freezing behaviour coexisting with spatially limited antiferromagnetic phase below 9.9 K in as-cast form. Thermal annealing effect is found to result in considerable changes in the magnetic ground state properties of the system. Though only one magnetic transition around 9.9 K is observed for as-cast compound, the annealed sample exhibits two distinct magnetic transitions; one around T N ~ 13.5 K and another around T f ~ 4 K. The magnetization measurements and zero field neutron diffraction study reveal that the high temperature transition is antiferromagnetic type, though of limited correlation length, while the low temperature transition corresponds to spin freezing behaviour. The ac susceptibility and heat capacity studies also confirm the existence of frustrated cluster glass state at lower temperature than the antiferromagnetic ordering temperature. Additionally, ac susceptibility data exhibits signature of an additional peak in the even lower temperature region (at 2.2 K for zero frequency) that tends to shift in opposite direction with frequency in contrast to that observed for conventional glassy transitions. The change in intrinsic local structural disorder of Ni and Si ions associated with annealing has been argued to be responsible for the different magnetic behaviour in as-cast and annealed samples.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Modification of RSF1010-Based Broad-Host-Range Plasmids for Improved Conjugation and Cyanobacterial Bioprospecting

To facilitate the genetic engineering of diverse cyanobacterial strains, we have modified broad-hostrange RSF1010-based plasmids to improve transmissibility, increase copy number, and facilitate cloning. RSF1010-based plasmids replicate in diverse bacterial strains but produce lowamounts of useable DNA for cloning. We previously engineered a mobAY25F mutation in RSF1010-based plasmids that improved cloning but decreased conjugation efficiency. Here, we engineered RSF1010-based plasmids to restore conjugation efficiency, which was demonstrated in three diverse laboratory strains of cyanobacteria. We then used an improved RSF1010-based plasmid in mating experiments with cultured samples of wild cyanobacteria. This plasmid, which confers antibiotic resistance and carries a yfp reporter gene, allowed selection of exconjugant cyanobacteria and facilitated the isolation of genetically tractable strains from mixed wild cultures. Improved RSF1010 vectors can be used for bioprospecting genetically tractable strains and are compatible with the CYANO-VECTOR cloning system, a versatile toolbox for constructing plasmids for cyanobacterial genetic engineering.

09 BIOMASS FUELS↗
DOE OSTI2013

Structural modifications in a Mn54Al43C3 melt-spun alloy induced by mechanical milling and subsequent annealing investigated by atom probe tomography

The structural changes upon milling and subsequent annealing of a Mn54Al43C3 alloy containing the intermetallic tetragonal L1(0) MnAl phase (tau phase) as the major phase were investigated by X-ray diffraction and atom probe tomography. The analyses show that milling the starting powder for 10 h leads to the nanostructuration of the sample. The milled sample is partly oxidised and contains both non oxidised Mn60 +/- 5Al40 +/- 5 regions and oxidised regions. Annealing the powder for 1 h at 500 degrees C leads to enrichment in Al of the oxidised regions, and to the phase transformation of the non-oxidised regions into a nano-structured beta-Mn-like phase with a composition close to Mn3Al2. (C) 2013 Elsevier B. V. All rights reserved.

Le Breton, JM↗
DOE OSTI2023

Toughening Sm–Co sintered magnets via microstructure modification with additives

We report the mechanical properties of the brittle Smsingle bondCo permanent magnets are of great practical significance. However, studies on the magnets have mostly focused on their magnetic properties. This paper reports the modified microstructure and refined unimodal grain size, enhanced flexural strength, and magnetic properties of Sm 2 (Co,Fe,Cu,Zr) 17 sintered magnets doped with La 2 O 3 , MgO, and CaF 2 fine particulates. The correlations between microstructure, phase composition, and mechanical and magnetic properties were studied. Doping of a small amount (e.g., 0.5–3 wt%) of La 2 O 3 , MgO, or CaF 2 fine particulates could significantly refine the unimodal grain sizes of the Smsingle bondCo magnets via the Zener pinning effect. Moreover, doping significantly improved the flexural strengths σ of the magnets. For example, the σ values of the magnets with 0.5 wt% MgO, 1 wt% La 2 O 3 , and 1 wt% CaF 2 were approximately 65%, 63%, and 42% higher than that of the reference magnet, respectively. Micromechanical simulations revealed that the fine particles of La 2 O 3 could deflect crack growth, while the CaF 2 particles could attract or arrest cracks during the fracture process. The mechanical strengthening effect was mainly due to grain size refinement. The Smsingle bondCo magnets with 0.5–1.5 wt% CaF2 and 0.5 wt% La 2 O 3 exhibited excellent magnetic properties while doping 1–3 wt% La2O3 and 0.5–3 wt% MgO deteriorated magnetic performance. The rational design of CaF 2 - or La 2 O 3 -doped microstructure can be an economical and effective method for producing toughened Sm–Co sintered magnets with high magnetic performance.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Comment on “Investigations on ion irradiation induced modifications in Th 5f occupancy in thoria,” by P. Jegadeesan, S. Amirthapandian, Gurpreet Kaur, D. Sanjay Kumar, Arindam Das, D.K. Avasthi, K. Ananthasivan, B.K. Panigrahi

The primary purpose of this letter is to address some issues raised in the paper by Jegadeesan et al. There are three salient points. (1) The Branching Ratio (BR) analysis of thorium dioxide is complicated by peaks from Extended X-Ray Absorption Fine Structure (EXAFS). (2) Uranium metal is not an LS coupling but rather a delocalized 5f case. (3) Radiation damage effects in the BR measurements are small but strong effects can be seen in Resonant Photoemission.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Interface Modifications by Anion Acceptors for High Energy Lithium Ion Batteries

Li-rich, Mn-rich (LMR) layered composite, for example, Li[Li0.2Ni0.2Mn0.6]O2, has attracted extensive interests because of its highest energy density among all cathode candidates for lithium ion batteries (LIB). However, capacity degradation and voltage fading are the major challenges associated with this series of layered composite, which plagues its practical application. Herein, we demonstrate that anion receptor, tris(pentafluorophenyl)borane ((C6F5)3B, TPFPB), substantially enhances the cycling stability and alleviates the voltage degradation of LMR. In the presence of 0.2 M TPFPB, Li[Li0.2Ni0.2Mn0.6]O2 shows capacity retention of 81% after 300 cycles. It is proposed that TPFPB effectively confines the highly active oxygen species released from structural lattice through its strong coordination ability and high oxygen solubility. The electrolyte decomposition caused by the oxygen species attack is therefore largely mitigated, forming reduced amount of byproducts on the cathode surface. Additionally, other salts such as insulating LiF derived from electrolyte decomposition are also soluble in the presence of TPFPB. The collective effects of TPFPB mitigate the accumulation of parasitic reaction products and stabilize the interfacial resistances between cathode and electrolyte during extended cycling, thus significantly improving the cycling performance of Li[Li0.2Ni0.2Mn0.6]O2.

anion receptor↗
DOE OSTI2014

From coin cells to 400 mAh pouch cells: Enhancing performance of high-capacity lithium-ion cells via modifications in electrode constitution and fabrication

In this article we describe efforts to improve performance and cycle life of cells containing Li1.2Ni0.15Mn0.55Co0.1O2-based positive and graphite-based negative electrodes. Initial work to identify high-performing materials, compositions, fabrication variables, and cycling conditions is conducted in coin cells. The resulting information is then used for the preparation of double-sided electrodes, assembly of pouch cells, and electrochemical testing. We report the cycling performance of cells with electrodes prepared under various conditions. Our data indicate that cells with positive electrodes containing 92 wt% Li1.2Ni0.15Mn0.55Co0.1O2, 4 wt% carbons (no graphite), and 4 wt% PVdF (92-4-4) show ~20% capacity fade after 1000 cycles in the 2.5-4.4V range, significantly better than our baseline cells that show the same fade after only 450 cycles. Our analyses indicate that the major contributors to cell energy fade are capacity loss and impedance rise. Therefore incorporating approaches that minimize capacity fade and impedance rise, such as electrode coatings and electrolyte additives, can significantly enhance calendar and cycle life of this promising cell chemistry.

Electrode fabrication↗