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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Shear Alignment of Diblock Copolymers for Patterning Nanowire Meshes

Metallic nanowire meshes are useful as cheap, flexible alternatives to indium tin oxide – an expensive, brittle material used in transparent conductive electrodes. We have fabricated nanowire meshes over areas up to 2.5 cm 2 by: 1) mechanically aligning parallel rows of diblock copolymer (diBCP) microdomains; 2) selectively infiltrating those domains with metallic ions; 3) etching away the diBCP template; 4) sintering to reduce ions to metal nanowires; and, 5) repeating steps 1 – 4 on the same sample at a 90° offset. We aligned parallel rows of polystyrene-b-poly(2-vinylpyridine) [PS(48.5 kDa)-b-P2VP(14.5 kDa)] microdomains by heating above its glass transition temperature (T g ≈ 100°C), applying mechanical shear pressure (33 kPa) and normal force (13.7 N), and cooling below T g . DiBCP samples were submerged in aqueous solutions of metallic ions (15 – 40 mM ions; 0.1 – 0.5 M HCl) for 30 – 90 minutes, which coordinate to nitrogen in P2VP. Subsequent ozone-etching and sintering steps yielded parallel nanowires. We aimed to optimize alignment parameters (e.g. shear and normal pressures, alignment duration, and PDMS thickness) to improve the quality, reproducibility, and scalability of meshes. We also investigated metals other than Pt and Au that may be patterned using this technique (Cu, Ag).

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

Strategy for alignment of electron beam trajectory in LEReC cooling section

We considered the steps required to align the electron beam trajectory through the LEReC cooling section. We devised a detailed procedure for the beam-based alignment of the cooling section solenoids. We showed that it is critical to have an individual control of each CS solenoid current. Finally, we modeled the alignment procedure and showed that with two BPM fitting the solenoid shift can be measured with 40 um accuracy and the solenoid inclination can be measured with 30 urad accuracy. These accuracies are well within the tolerances of the cooling section solenoid alignment.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Aligned carbon nanotubes for 1,000x improvement in computing (CRADA Final Report)

As part of the Cyclotron Road program, the Aligned Carbon team worked to improve and bring to market their technology to manufacture carbon nanotubes (CNTs) for integrated circuits. There are multiple applications which can benefit from the use of CNT based transistors in integrated circuits, including high performance computing, RF data transmission, and biosensing. Each of these applications faces a problem of poor starting CNT material to come to market. Aligned Carbon offers material with the highest ceiling of performance based around a fully aligned, uniform, on-wafer growth of CNTs and our proprietary purification process to remove metallic CNTs leaving only the semi-conducting ones behind. Further, Aligned Carbon has been guided by scalable manufacturing processes that will fit seamlessly into the integrated circuit foundry model of chip fabrication.

36 MATERIALS SCIENCE↗
NASA NTRS2014

Ambient Optomechanical Alignment and Pupil Metrology for the Flight Instruments Aboard the James Webb Space Telescope

The James Webb Space Telescope science instruments are in the final stages of being integrated into the Integrated Science Instrument Module (ISIM) element. Each instrument is tied into a common coordinate system through mechanical references that are used for optical alignment and metrology within ISIM after element-level assembly. In addition, a set of ground support equipment (GSE) consisting of large, precisely calibrated, ambient, and cryogenic structures are used as alignment references and gauges during various phases of integration and test (I&T). This GSE, the flight instruments, and ISIM structure feature different types of complimentary metrology targeting. These GSE targets are used to establish and track six degrees of freedom instrument alignment during I&T in the vehicle coordinate system (VCS). This paper describes the optomechanical metrology conducted during science instrument integration and alignment in the Spacecraft Systems Development and Integration Facility (SSDIF) cleanroom at NASA Goddard Space Flight Center (GSFC). The measurement of each instrument's ambient entrance pupil location in the telescope coordinate system is discussed. The construction of the database of target locations and the development of metrology uncertainties is also discussed.

Optomechanical Alignment↗
NASA NTRS2016

The Alignment and Phasing System for the Thirty Meter Telescope: Risk Mitigation and Status Update

Alignment and Phasing System (APS) is responsible for the optical alignment via starlight of the approximately 12,000 degrees of freedom of the primary, secondary and tertiary mirrors of Thirty Meter Telescope (TMT). APS is based on the successful Phasing Camera System (PCS) used to align the Keck Telescopes. Since the successful APS conceptual design in 2007, work has concentrated on risk mitigation, use case generation, and alignment algorithm development and improvement. Much of the risk mitigation effort has centered around development and testing of prototype APS software which will replace the current PCS software used at Keck. We present an updated APS design, example use cases and discuss, in detail, the risk mitigation efforts.

Optical Alignment↗
DOE OSTI2016

Morphing Downwind-Aligned Rotor Concept Based on a 13-MW Wind Turbine

To alleviate the mass-scaling issues associated with conventional upwind rotors of extreme-scale wind turbines (>/=10 MW), a morphing downwind-aligned rotor (MoDaR) concept is proposed herein. The concept employs a downwind rotor with blades whose elements are stiff (no intentional flexibility) but with hub-joints that can be unlocked to allow for moment-free downwind alignment. Aligning the combination of gravitational, centrifugal and thrust forces along the blade path reduces downwind cantilever loads, resulting in primarily tensile loading. For control simplicity, the blade curvature can be fixed with a single morphing degree of freedom using a near-hub joint for coning angle: 22 degrees at rated conditions. The conventional baseline was set as the 13.2-MW Sandia 100-m all glass blade in a three-bladed upwind configuration. To quantify potential mass savings, a downwind load-aligning, two-bladed rotor was designed. Because of the reduced number of blades, the MoDaR concept had a favorable 33% mass reduction. The blade reduction and coning led to a reduction in rated power, but morphing increased energy capture at lower speeds such that both the MoDaR and conventional rotors have the same average power: 5.4 MW. A finite element analysis showed that quasi-steady structural stresses could be reduced, over a range of operating wind speeds and azimuthal angles, despite the increases in loading per blade. However, the concept feasibility requires additional investigation of the mass, cost and complexity of the morphing hinge, the impact of unsteady aeroelastic influence because of turbulence and off-design conditions, along with system-level Levelized Cost of Energy analysis.

17 WIND ENERGY↗
DOE OSTI2014

Impersonating the Standard Model Higgs boson: Alignment without decoupling

In models with an extended Higgs sector there exists an alignment limit, in which the lightest CP-even Higgs boson mimics the Standard Model Higgs. The alignment limit is commonly associated with the decoupling limit, where all non-standard scalars are significantly heavier than the Z boson. However, alignment can occur irrespective of the mass scale of the rest of the Higgs sector. In this work we discuss the general conditions that lead to “alignment without decoupling”, therefore allowing for the existence of additional non-standard Higgs bosons at the weak scale. The values of tan β for which this happens are derived in terms of the effective Higgs quartic couplings in general two-Higgs-doublet models as well as in supersymmetric theories, including the MSSM and the NMSSM. In addition, we study the information encoded in the variations of the SM Higgs-fermion couplings to explore regions in the m A – tan β parameter space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

First measurement of D* + vector meson spin alignment in Pb–Pb collisions at $\sqrt{{s}_{\text{NN}}}={5}.0{2}$ TeV

The first measurement of prompt D *+ -meson spin alignment in ultrarelativistic heavy-ion collisions with respect to the direction orthogonal to the reaction plane is presented. The spin alignment is quantified by measuring the element ρ 00 of the diagonal spin-density matrix for prompt D *+ mesons with 4 < p T < 30 GeV/c in two rapidity intervals, |y| < 0.3 and 0.3 < |y| < 0.8, in central (0–10%) and midcentral (30–50%) Pb–Pb collisions at $\sqrt{{s}_{\text{NN}}}={5}.0{2}$ TeV. Evidence of spin alignment ρ 00 > 1/3 has been found for p T > 15 GeV/c and 0.3 < |y| < 0.8 with a significance of 3.1σ. The measured spin alignment of prompt D *+ mesons is compared with the one of inclusive J/ψ mesons measured at forward rapidity (2.5 < y < 4).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Fabrication and Characterization of Aligned YBa{sub 2}Cu{sub 3}O{sub 7 − δ} Superconductor Electrospun Nanofibers and Twisted Yarn Based on PVA

YBa{sub 2}Cu{sub 3}O{sub 7 − δ} (YBCO) superconducting twisted yarns from electrospun aligned nanofibers are produced with a critical transition temperature of T{sub c} = 92 K. A solution of PVA and Y–Ba–Cu acetates are used as a precursor in the electrospinning to prepare aligned nanofibers and twisted yarns. The aligned nanofibers and twisted yarns are then pyrolysed to remove PVA and sintered to obtain a superconducting phase. Finally, before and after sintering, the aligned nanofibers and twisted yarns are studied by SEM, XRD, and AC magnetic susceptibility techniques. Results are presented in this paper.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Integrating helicoid channels for passive control of fiber alignment in direct-write 3D printing

3D printing of fiber-reinforced composites has been receiving increasing attention as an efficient additive approach enabling lightweight, functional, and high-performance components required for industrial applications. The properties of fiber composites significantly depend on internal microstructures, including fiber orientation, distribution, and degree of alignment. Although multiple strategies have been introduced for controlling the fiber composites microstructures, these strategies are mostly active approaches relying on additional control of mechatronics parts, external forces, or intentionally introduced unstable flows inside narrow nozzles. These methods suffer from higher risk of nozzle clogging and requiring extra parts in 3D printing. Here, we introduce helicoid channels into extrusion system as a passive approach to control the fiber alignment without any additional moving parts in direct-write 3D printing. The helicoid channels automatically guide the composite inks and align fibers before flowing into narrow nozzle space, avoiding clogging and improving printability. The analyses indicate that both helicoid surface to volume ratio and helix angle affect the pre-alignment of fibers, leading to tunable mechanical properties of printed fiber-reinforced composites with increased stiffness and strength up to 77.6% and 47.8%, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Alignment Focus of Daily Image Guidance for Concurrent Treatment of Prostate and Pelvic Lymph Nodes

Purpose: To determine the dosimetric impact of daily imaging alignment focus on the prostate soft tissue versus the pelvic bones for the concurrent treatment of the prostate and pelvic lymph nodes (PLN) and to assess whether multileaf collimator (MLC) tracking or adaptive planning (ART) is necessary with the current clinical planning margins of 8 mm/6 mm posterior to the prostate and 5 mm to the PLN. Methods and Materials: A total of 124 kilovoltage cone-beam computed tomography (kV-CBCT) images from 6 patients were studied. For each KV-CBCT, 4 plans were retrospectively created using an isocenter shifting method with 2 different alignment focuses (prostate, PLN), an MLC shifting method, and the ART method. The selected dosimetric endpoints were compared among these plans. Results: For the isoshift contour, isoshift bone, MLC shift, and ART plans, D99 of the prostate was ≥97% of the prescription dose in 97.6%, 73.4%, 98.4%, and 96.8% of 124 fractions, respectively. Accordingly, D99 of the PLN was ≥97% of the prescription dose in 98.4%, 98.4%, 98.4%, and 100% of 124 fractions, respectively. For the rectum, D5 exceeded 105% of the planned D5 (and D5 of ART plans) in 11% (4%), 10% (2%), and 13% (5%) of 124 fractions, respectively. For the bladder, D5 exceeded 105% of the planned D5 (and D5 of ART) plans in 0% (2%), 0% (2%), and 0% (1%) of 124 fractions, respectively. Conclusion: For concurrent treatment of the prostate and PLN, with a planning margin to the prostate of 8 mm/6 mm posterior and a planning margin of 5 mm to the PLN, aligning to the prostate soft tissue can achieve adequate dose coverage to the both target volumes; aligning to the pelvic bone would result in underdosing to the prostate in one-third of fractions. With these planning margins, MLC tracking and ART methods have no dosimetric advantages.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Alignment of Iron Nanoparticles in a Magnetic Field Due to Shape Anisotropy

During high magnetic field processing there is evidence for alignment of non-spherical metallic particles above the Curie temperature in alloys with negligible magneto-crystalline anisotropy. The main driving force for alignment is the magnetic shape anisotropy. Current understanding of the phenomenon is not adequate to quantify the effect of particle size, aspect ratio, temperature and the magnetic field on particle alignment. We demonstrate a Monte Carlo approach coupled with size scaling to show the conditions under which alignment is possible.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Band alignment of ultra-thin hetero-structure ZnO/TiO{sub 2} junction

Graphical abstract: - Highlights: • Band alignment at the ZnO/TiO{sub 2} hetero-structural interface with different ZnO coating thickness was studied. • The valence band offset was decreased with increased ZnO coating layer thickness. • The interface dipole was responsible for the decreased band offset. - Abstract: The band alignment at the ZnO/TiO{sub 2} hetero-structure interface was measured by high resolution X-ray photoelectron spectroscopy. The valence band offset (E{sub ZnO}−E{sub TiO{sub 2}}){sub Valence} was linearly changed from 0.27 to 0.01 eV at the interface with increased ZnO coating thickness from 0.7 to 7 nm. The interface dipole presented at the ZnO/TiO{sub 2} interface was responsible for the decreased band offset. The band alignment of the ZnO/TiO{sub 2} heterojunction is a type II alignment.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Multifield optimization intensity-modulated proton therapy (MFO-IMPT) for prostate cancer: Robustness analysis through simulation of rotational and translational alignment errors

To evaluate the dosimetric consequences of rotational and translational alignment errors in patients receiving intensity-modulated proton therapy with multifield optimization (MFO-IMPT) for prostate cancer. Ten control patients with localized prostate cancer underwent treatment planning for MFO-IMPT. Rotational and translation errors were simulated along each of 3 axes: anterior-posterior (A-P), superior-inferior (S-I), and left-right. Clinical target-volume (CTV) coverage remained high with all alignment errors simulated. Rotational errors did not result in significant rectum or bladder dose perturbations. Translational errors resulted in larger dose perturbations to the bladder and rectum. Perturbations in rectum and bladder doses were minimal for rotational errors and larger for translational errors. Rectum V45 and V70 increased most with A-P misalignment, whereas bladder V45 and V70 changed most with S-I misalignment. The bladder and rectum V45 and V70 remained acceptable even with extreme alignment errors. Even with S-I and A-P translational errors of up to 5 mm, the dosimetric profile of MFO-IMPT remained favorable. MFO-IMPT for localized prostate cancer results in robust coverage of the CTV without clinically meaningful dose perturbations to normal tissue despite extreme rotational and translational alignment errors.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2013

Enzyme sequence similarity improves the reaction alignment method for cross-species pathway comparison

Pathway-based information has become an important source of information for both establishing evolutionary relationships and understanding the mode of action of a chemical or pharmaceutical among species. Cross-species comparison of pathways can address two broad questions: comparison in order to inform evolutionary relationships and to extrapolate species differences used in a number of different applications including drug and toxicity testing. Cross-species comparison of metabolic pathways is complex as there are multiple features of a pathway that can be modeled and compared. Among the various methods that have been proposed, reaction alignment has emerged as the most successful at predicting phylogenetic relationships based on NCBI taxonomy. We propose an improvement of the reaction alignment method by accounting for sequence similarity in addition to reaction alignment method. Using nine species, including human and some model organisms and test species, we evaluate the standard and improved comparison methods by analyzing glycolysis and citrate cycle pathways conservation. In addition, we demonstrate how organism comparison can be conducted by accounting for the cumulative information retrieved from nine pathways in central metabolism as well as a more complete study involving 36 pathways common in all nine species. Our results indicate that reaction alignment with enzyme sequence similarity results in a more accurate representation of pathway specific cross-species similarities and differences based on NCBI taxonomy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Reconfigurable structural color by reversible switching of colloidal discoid liquid crystal alignment

Combining the effects of alternating-current (AC) electric fields and sedimentation reconfigures colloidal discoids between planar and homeotropic orientational alignments, thereby controlling the material’s structural color. Here, we self-assemble micrometer-size polystyrene discoids in an isopropanol-water mixture. After sedimentation, the discoids adopt a homeotropic alignment, with the minor axis perpendicular to the substrate. Adding an AC electric field (1 kHz) of ≥0.50 V switches the discoids to planar alignment—with the minor axis parallel to the substrate—within ∼100 s. Removing the field switches them back to homeotropic alignment within ∼300 s. Kinetic modeling of the field-induced torques yields good agreement with these measurements. The peak wavelength and intensity of the crystal’s diffraction response shift significantly upon reconfiguration; scattering simulation predicts these shifts. The reconfiguration is maintained for at least 10 cycles. This method is a simple, scalable avenue to reconfigure the optical properties of colloidal crystals produced from simple dielectric spheroids.

colloidal crystals↗
DOE OSTI2026

Constructing field-aligned coordinate systems for gyrokinetic simulations of tokamaks in X-point geometries

Structures in tokamak plasmas are elongated along the direction of the magnetic field and short in the directions perpendicular to the magnetic field. Many tokamak simulation codes take advantage of this by using a field-aligned coordinate system. However, field-aligned coordinate systems have a coordinate singularity at magnetic X-points where the poloidal magnetic field vanishes, which makes it difficult to use field-aligned coordinate systems when simulating the core and scrape-off layer simultaneously. Here, we present an algorithm for grid generation and computing geometric quantities in a standard field-aligned coordinate system that avoids the singularity and allows one to conduct two-dimensional gyrokinetic axisymmetric simulations in X-point geometries. Convergence tests of advection, boundary value problems and geometric quantities all show greater than first-order convergence even in the vicinity of the X-point. We also demonstrate the geometric consistency of our algorithm with an example simulation of the spherical tokamak for energy production, which shows machine-precision particle conservation.

fusion plasma↗
DOE OSTI2019

Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes

The performance of ion-exchange membranes in fuel cells is critically linked to their ion-conducting morphology. In this report, we analyzed the connectivity of anion-exchange membranes (AEMs) by electrostatic force microscopy (EFM). As a tapping-mode AFM-based technique, EFM probes height, phase, and electrostatic force gradient through two-pass interleave scans, which reveals the direct relationship between membrane surface morphology and connectivity of the ionic domain. The AEMs are diblock copolymers of a polyisoprene (PIp) block and a polystyrenic block containing the phosphonium ion (P(R3P+)MS). Different alignments of cylinders were observed in the bulk and on the surface for AEMs with different ionexchange capacities (IECs) and preparation methods. The impacts of the cylinder alignment on the connectivity of the ionic domain were then investigated by EFM. For AEM 13 with IEC = 0.44 mmol/g and a hexagonal morphology, cylinders aligned parallel to the surface, which led to many disconnected regions observed throughout the membrane. In contrast, the perpendicularly aligned channels of AEM 16 with IEC = 0.87 mmol/g consisted only of a well-connected ionic phase throughout the membrane.

25 ENERGY STORAGE↗