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NASA NTRS1985

The SIFT hardware/software systems. Volume 2: Software listings

This document contains software listings of the SIFT operating system and application software. The software is coded for the most part in a variant of the Pascal language, Pascal*. Pascal* is a cross-compiler running on the VAX and Eclipse computers. The output of Pascal* is BDX-390 assembler code. When necessary, modules are written directly in BDX-390 assembler code. The listings in this document supplement the description of the SIFT system found in Volume 1 of this report, A Detailed Description.

Palumbo, Daniel L.↗

DOE OSTI2024

One-Pot Self-Assembly of Sequence-Controlled Mesoporous Heterostructures via Structure-Directing Agents

Multimaterial heterostructures have led to characteristics surpassing the individual components. Nature controls the architecture and placement of multiple materials through biomineralization of nanoparticles (NPs); however, synthetic heterostructure formation remains limited and generally departs from the elegance of self-assembly. Here, in this study, a class of block polymer structure-directing agents (SDAs) are developed containing repeat units capable of persistent (covalent) NP interactions that enable the direct fabrication of nanoscale porous heterostructures, where a single material is localized at the pore surface as a continuous layer. This SDA binding motif (design rule 1) enables sequence-controlled heterostructures, where the composition profile and interfaces correspond to the synthetic addition order. This approach is generalized with 5 material sequences using an SDA with only persistent SDA-NP interactions (“P-NP 1 –NP 2 ”; NP i = TiO 2 , Nb 2 O 5 , ZrO 2 ). Expanding these polymer SDA design guidelines, it is shown that the combination of both persistent and dynamic (noncovalent) SDA-NP interactions (“PD-NP 1 –NP 2 ”) improves the production of uniform interconnected porosity (design rule 2). The resulting competitive binding between two segments of the SDA (P- vs D-) requires additional time for the first NP type (NP 1 ) to reach and covalently attach to the SDA (design rule 3). The combination of these three design rules enables the direct self-assembly of heterostructures that localize a single material at the pore surface while preserving continuous porosity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1996

Statistical Tolerance and Clearance Analysis for Assembly

Tolerance is inevitable because manufacturing exactly equal parts is known to be impossible. Furthermore, the specification of tolerances is an integral part of product design since tolerances directly affect the assemblability, functionality, manufacturability, and cost effectiveness of a product. In this paper, we present statistical tolerance and clearance analysis for the assembly. Our proposed work is expected to make the following contributions: (i) to help the designers to evaluate products for assemblability, (ii) to provide a new perspective to tolerance problems, and (iii) to provide a tolerance analysis tool which can be incorporated into a CAD or solid modeling system.

statistical tolerance clearance analysis Monte-Car↗

NASA NTRS2012

Process Sensitivity, Performance, and Direct Verification Testing of Adhesive Locking Features

Phase I: The use of adhesive locking features or liquid locking compounds (LLCs) (e.g., Loctite) as a means of providing a secondary locking feature has been used on NASA programs since the Apollo program. In many cases Loctite was used as a last resort when (a) self-locking fasteners were no longer functioning per their respective drawing specification, (b) access was limited for removal & replacement, or (c) replacement could not be accomplished without severe impact to schedule. Long-term use of Loctite became inevitable in cases where removal and replacement of worn hardware was not cost effective and Loctite was assumed to be fully cured and working. The NASA Engineering & Safety Center (NESC) and United Space Alliance (USA) recognized the need for more extensive testing of Loctite grades to better understand their capabilities and limitations as a secondary locking feature. These tests, identified as Phase I, were designed to identify processing sensitivities, to determine proper cure time, the correct primer to use on aerospace nutplate, insert and bolt materials such as A286 and MP35N, and the minimum amount of Loctite that is required to achieve optimum breakaway torque values. The .1900-32 was the fastener size tested, due to wide usage in the aerospace industry. Three different grades of Loctite were tested. Results indicate that, with proper controls, adhesive locking features can be successfully used in the repair of locking features and should be considered for design. Phase II: Threaded fastening systems used in aerospace programs typically have a requirement for a redundant locking feature. The primary locking method is the fastener preload and the traditional redundant locking feature is a self-locking mechanical device that may include deformed threads, non-metallic inserts, split beam features, or other methods that impede movement between threaded members. The self-locking resistance of traditional locking features can be directly verified during assembly by measuring the dynamic prevailing torque. Adhesive locking features or LLCs are another method of providing redundant locking, but a direct verification method has not been used in aerospace applications to verify proper installation when using LLCs because of concern for damage to the adhesive bond. The reliability of LLCs has also been questioned due to failures observed during testing with coupons for process verification, although the coupon failures have often been attributed to a lack of proper procedures. It is highly desirable to have a direct method of verifying the LLC cure or bond integrity. The purpose of the Phase II test program was to determine if the torque applied during direct verification of an adhesive locking feature degrades that locking feature. This report documents the test program used to investigate the viability of such a direct verification method. Results of the Phase II testing were positive, and additional investigation of direct verification of adhesive locking features is merited.

Golden, Johnny L.↗

DOE OSTI2023

Membrane Adsorbents Comprising Self-Assembled Inorganic Nanocages (SINCs) for Super-fast Direct Air Capture Enabled by Passive Cooling

The objectives of the proposed project were to develop highly porous membrane adsorbents comprising CO 2 -philic polymers and self-assembled inorganic nanocages (SINCs) for rapid temperature swing adsorption using electricity-free solar heating and radiative cooling, enabling an economically viable approach for direct air capture (DAC). Our core technical activities combine three key innovations. (1) Highly porous flat-sheet membrane adsorbents contain CO 2 -philic amines that can be easily produced using a phase inversion method. (2) CO 2 -philic SINCs can be easily dispersed in the polymers with great stability (compared with the metal-organic frameworks or MOFs). (3) The adsorption and desorption are integrated with solar heating and radiative cooling for rapid continuous operation, in contrast to traditional long-cycle separate operation. The membrane adsorbents containing amines, polymers, and SINCs were produced using a one-step industrial process. The porous membranes coupled with porous SINCs offer low resistance for gas flow and fast CO 2 sorption/desorption cycles, while the incorporation of the additional amine groups provides high CO 2 sorption capacity. The key achievements are summarized below. (1) Membrane adsorbents with high PEI loading (>40%), high porosity of >80%, and low gasflow resistance were prepared in one step using commercially available, low-cost materials. (2) Membrane adsorbents based on Solupor and PEI show CO 2 sorption capacity of >1.5 mmol/g using air containing 400 ppm at a relative humidity of 15%. (3) Effect of the adsorbent compositions (such as PEI type, PEI content, SINC content, porosity) on the CO 2 sorption was systematically investigated. (4) Effect of the processing conditions (such as CO 2 content, temperature, and relative humidity) on the CO 2 sorption was systematically investigated; (5) The stability of the membrane adsorption against many cycles of sorption and desorption was studied. The higher molecular weight of PEI (PEI25k) shows better stability than PEI800. (6) Advanced materials with radiative cooling were developed, which can decrease the temperature by 5-7 °C compared to the ambient temperature. (7) Preliminary techno-economic analysis shows that our process may achieve a capture cost of $1,343/tonne CO 2 with a total OPEX cost of $1,112/tonne CO 2 . The adsorbent replacement cost accounted for 52% of the total OPEX cost. Membrane adsorbents with lower costs and longer operation life can significantly decrease the cost. The proposed project directly addresses the requirement of DE-FOA-0002188, i.e., novel materials with CO 2 adsorption capacity for direct air capture with integrated solar heating and radiative cooling to reduce the cost of the DAC. Our future work will focus on the development of low-cost adsorbents that can be stable at the sorption and desorption conditions for long term.

14 SOLAR ENERGY↗

NASA NTRSDate not supplied

In-Space Modular Assembly: An Approach for Reliable, Affordable, Precision Space Apertures

In-space assembly will revolutionize the creation, upgrade, and evolution of future space systems. In-space assembly represents an alternative deployment strategy that is not constrained by the requirement of using a single launch vehicle and enables a greater freedom of design for the initial emplacement of assets and their evolution over time. In-space assembly enables assets, such as observatories and science platforms, to become persistent, evolving over time like their terrestrial counterparts. Also, in-space assembly provides a direct path for utilization of in-space manufactured components designed exclusively for the operational environment. To highlight the advantages of an in-space assembly approach, the modular assembly of a 3 m to 4 m precision optical aperture based on thin meniscus technology coupled with structurally efficient TriTruss modules is presented. The 3 m to 4 m aperture stows compactly within two standard ride share slots (0.61 m by 0.71 m by 0.97 m). Placing instruments and the robotic system used for assembly in an adjacent ride share slot enables a capable observatory to be placed into service via modest ride share opportunities. Further, recent hardware assembly tests of similar modules and progress toward hardware tests to validate the overall architecture via diffraction limited testing will be summarized.

Design↗

NASA NTRSDate not supplied

In-Space Modular Assembly: An Approach for Reliable, Affordable, Precision Space Apertures

Design↗

NASA NTRS2017

Band-to-Band Misregistration of the Images of MODIS Onboard Calibrators and Its Impact on Calibration

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard Terra and Aqua satellites are radiometrically calibrated on-orbit with a set of onboard calibrators (OBCs), including a solar diffuser, a blackbody, and a space view port through which the detectors can view the dark space. As a whisk-broom scanning spectroradiometer, thirty-six MODIS spectral bands are assembled in the along-scan direction on four focal plane assemblies (FPAs). These bands capture images of the same target sequentially with the motion of a scan mirror. Then the images are coregistered onboard by delaying the appropriate band-dependent amount of time, depending on the band locations on the FPA. While this coregistration mechanismis functioning well for the far-field remote targets such as earth view scenes or the moon, noticeable band-to-band misregistration in the along-scan direction has been observed for near field targets, particularly in OBCs. In this paper, the misregistration phenomenon is presented and analyzed. It is concluded that the root cause of the misregistration is that the rotating element of the instrument, the scan mirror, is displaced from the focus of the telescope primary mirror. The amount of the misregistrationis proportional to the band location on the FPA and is inversely proportional to the distance between the target and the scan mirror. The impact of this misregistration on the calibration of MODIS bands is discussed. In particular, the calculation of the detector gain coefficient m1of bands 8-16 (412 nm 870 nm) is improved by up to 1.5% for Aqua MODIS.

Wang, Zhipeng↗

NASA NTRS2013

Next-Generation MKIII Lightweight HUT/Hatch Assembly

The MK III (H-1) carbon-graphite/ epoxy Hard Upper Torso (HUT)/Hatch assembly was designed, fabricated, and tested in the early 1990s. The spacesuit represented an 8.3 psi (≈58 kPa) technology demonstrator model of a zero prebreathe suit. The basic torso shell, brief, and hip areas of the suit were composed of a carbon-graphite/epoxy composite lay-up. In its current configuration, the suit weighs approximately 120 lb (≈54 kg). However, since future planetary suits will be designed to operate at 0.26 bar (≈26 kPa), it was felt that the suit's re-designed weight could be reduced to 79 lb (≈35 kg) with the incorporation of lightweight structural materials. Many robust, lightweight structures based on the technologies of advanced honeycomb materials, revolutionary new composite laminates, metal matrix composites, and recent breakthroughs in fullerene fillers and nanotechnology lend themselves well to applications requiring materials that are both light and strong. The major problem involves the reduction in weight of the HUT/ Hatch assembly for use in lunar and/or planetary applications, while at the same time maintaining a robust structural design. The technical objective is to research, design, and develop manufacturing methods that support fa b rica - tion of a lightweight HUT/Hatch assembly using advanced material and geometric redesign as necessary. Additionally, the lightweight HUT/Hatch assembly will interface directly with current MK III hardware. Using the new operating pressure and current MK III (H-1) interfaces as a starting block, it is planned to maximize HUT/Hatch assembly weight reduction through material selection and geometric redesign. A hard upper torso shell structure with rear-entry closure and corresponding hatch will be fabricated. The lightweight HUT/Hatch assembly will retrofit and interface with existing MK III (H-1) hardware elements, providing NASA with immediate "plug-andplay" capability. NASA crewmembers will have a lightweight, robust, life-support system that will minimize fatigue during extraterrestrial surface sojourns. Its unique feature is the utilization of a new and innovative family of materials used by the aerospace industry, which at the time of this reporting has not been used for the proposed application.

McCarthy, Mike↗

DOE OSTI2022

Medial packing and elastic asymmetry stabilize the double-gyroid in block copolymers

Triply-periodic networks are among the most complex and functionally valuable self-assembled morphologies, yet they form in nearly every class of biological and synthetic soft matter building blocks. In contrast to simpler assembly motifs – spheres, cylinders, layers – networks require molecules to occupy variable local environments, confounding attempts to understand their formation. Here, we examine the double-gyroid network phase by using a geometric formulation of the strong stretching theory of block copolymer melts, a prototypical soft self-assembly system. The theory establishes the direct link between molecular packing, assembly thermodynamics and the medial map, a generic measure of the geometric center of complex shapes. We show that “medial packing” is essential for stability of double-gyroid in strongly-segregated melts, reconciling a long-standing contradiction between infinite- and finite-segregation theories. Additionally, we find a previously unrecognized non-monotonic dependence of network stability on the relative entropic elastic stiffness of matrix-forming to tubular-network forming blocks. The composition window of stable double-gyroid widens for both large and small elastic asymmetry, contradicting intuitive notions that packing frustration is localized to the tubular domains. This study demonstrates the utility of optimized medial tessellations for understanding soft-molecular assembly and packing frustration via an approach that is readily generalizable far beyond gyroids in neat block copolymers.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Unraveling the Dynamics of Nucleosome Arrays

The organization of genomic DNA into chromatin is a fundamental determinant of genome stability, regulation, and cellular function. Nucleosomes, the basic repeating units of chromatin, assemble into higher-order structures whose organization and heterogeneity remain difficult to characterize using conventional ensemble-averaged techniques. A key need in the field is the development of experimental approaches capable of directly visualizing nucleosome assemblies and their structural variability at the single-molecule level. This LDRD Lab-Wide project focused on establishing and evaluating atomic force microscopy (AFM)–based approaches for the characterization of nucleosome assemblies. The work emphasized experimental workflows for preparing, imaging, and assessing multi-nucleosome systems, rather than isolated single nucleosomes. Through method development and exploratory measurements, the project demonstrated the feasibility of applying scanning probe microscopy to investigate chromatin-relevant assemblies and provided preliminary insight into the strengths and limitations of this approach for future quantitative studies. Results and lessons learned from this effort were disseminated to the broader scientific community through multiple national conference presentations, helping to position LLNL for continued work in chromatin and genome organization research.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS1984

Fuel cell design and assembly

The present invention is directed to a novel bipolar cooling plate, fuel cell design and method of assembly of fuel cells. The bipolar cooling plate used in the fuel cell design and method of assembly has discrete opposite edge and means carried by the plate defining a plurality of channels extending along the surface of the plate toward the opposite edges. At least one edge of the channels terminates short of the edge of the plate defining a recess for receiving a fastener.

Myerhoff, Alfred↗

NASA NTRS1998

Synopsis of Direct and Indirect Lightning Effects on Composite Materials

NASA's Space Environments and Effects (SEE) Program funded a study on electromagnetic environmental effect issues of composite materials used by the aerospace industry. The results of which are published by Ross Evans, Tec-Masters Inc., in NASA-CR-4783, "Test Report - Direct and Indirect Lightning Effects on Composite Materials." Indirect effects include the electric and magnetic field shielding provided by a composite material illuminated by a near or direct lightning strike. Direct effects includes the physical damage of composites and/or assembly joint with a direct strike injection. This paper provides a synopsis of NASA-CR-4783. A short description is provided of the direct and indirect tests performed during the sturdy. General results and design guidelines are discussed.

Tony Clark↗

DOE OSTI2022

Expanding the Scope of Pnictogen‐Assisted Cyclophane Self‐Assembly

Cyclophanes are a fundamentally interesting class of compounds that host a wide range of unique and emergent properties. Furthermore, synthesis of complex and/or functionalized cyclophanes can often suffer from harsh reaction conditions, long reaction times, and sometimes low yields using stepwise methods. We have previously reported an efficient, high-yielding, metalloid-directed self-assembly method to prepare disulfide, thioether, and hydrocarbon cyclophanes and cages that feature mercaptomethyl-arenes as starting materials. Herein, we report the synthesis of 21 new disulfide and thioether assemblies that expand this high yielding self-assembly method to a wide breadth of macrocycles and cages with diverse structures. Remarkably, the high-yielding, efficient syntheses still proceed under dynamic covalent control using electron-deficient, heteroaryl, cycloalkyl, spiro, and even short alkenyl/alkynyl substrates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Discovery of Self-Assembling π-Conjugated Peptides by Active Learning-Directed Coarse-Grained Molecular Simulation

Electronically active organic molecules have demonstrated great promise as novel soft materials for energy harvesting and transport. Self-assembled nanoaggregates formed from π-conjugated oligopeptides composed of an aromatic core flanked by oligopeptide wings offer emergent optoelectronic properties within a water-soluble and biocompatible substrate. Nanoaggregate properties can be controlled by tuning core chemistry and peptide composition, but the sequence–structure–function relations remain poorly characterized. Here, we employ coarse-grained molecular dynamics simulations within an active learning protocol employing deep representational learning and Bayesian optimization to efficiently identify molecules capable of assembling pseudo-1D nanoaggregates with good stacking of the electronically active π-cores. We consider the DXXX-OPV3-XXXD oligopeptide family, where D is an Asp residue and OPV3 is an oligophenylenevinylene oligomer (1,4-distyrylbenzene), to identify the top performing XXX tripeptides within all 20 3 = 8000 possible sequences. By direct simulation of only 2.3% of this space, we identify molecules predicted to exhibit superior assembly relative to those reported in prior work. Spectral clustering of the top candidates reveals new design rules governing assembly. This work establishes new understanding of DXXX-OPV3-XXXD assembly, identifies promising new candidates for experimental testing, and presents a computational design platform that can be generically extended to other peptide-based and peptide-like systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Tubulin Double Helix: Lateral and Longitudinal Curvature Changes of Tubulin Protofilament

By virtue of their native structures, tubulin dimers are protein building blocks that are naturally pre-programmed to assemble into cytoskeletal polymers known as microtubules (MTs). Here we demonstrate polycation-directed (i.e. electrostatically tunable) assembly of tubulins through tubulin protofilament conformational changes in the longitudinal and lateral directions, creating novel tubulin double helices and various tubular architectures. Synchrotron small angle X-ray scattering and transmission electron microscopy reveal a remarkable range of nanoscale assembly structures: single- and double-layered double-helix tubulin tubules. The phase transitions from MTs into the new assemblies are dependent on the size and concentration of polycations. Two characteristic scales that determine the number of observed phases are the size of polycation compared to the size of tubulin (≈4 nm) and MT diameter (≈25 nm). This work suggests the feasibility of “programmable breakdown” of protein nanotubes, tearing MTs into double-stranded tubulins and building up previously undiscovered nanostructures, by using polycations with scissor- and glue-like properties. Importantly, we define a new role of tubulins as two-dimensionally shape-controllable building blocks for novel supramolecular architectures. Furthermore, these findings provide insight into the design of protein-based functional materials, for example, as metallization templates for nanoscale electronic devices, kinesin motor-driving molecular screws, and anticancer drug delivery vehicles.

2D shape‐control↗

DOE OSTI2021

Innovative nanopore sequencing technology including a self-assembled porous membrane

Methods and apparatus for long read, label-free, optical nanopore long chain molecule sequencing. In general, the present disclosure describes a novel sequencing technology based on the integration of nanochannels to deliver single long-chain molecules with widely spaced (>wavelength), ˜1-nm aperture “tortuous” nanopores that slow translocation sufficiently to provide massively parallel, single base resolution using optical techniques. A novel, directed self-assembly nanofabrication scheme using simple colloidal nanoparticles is used to form the nanopore arrays atop nanochannels that unfold the long chain molecules. At the surface of the nanoparticle array, strongly localized electromagnetic fields in engineered plasmonic/polaritonic structures allow for single base resolution using optical techniques.

Brueck, Steven R. J.↗

DOE OSTI2020

Evaporation-Induced Vertical Alignment Enabling Directional Ion Transport in a 2D-Nanosheet-Based Battery Electrode

2D nanosheets have been widely explored as electrode materials owing to their extraordinarily high electrochemical activity and fast solid-state diffusion. However, the scalable electrode fabrication based on this type of material usually suffers from severe performance losses due to restricted ion-transport kinetics in a large thickness. Here, a novel strategy based on evaporation-induced assembly to enable directional ion transport via forming vertically aligned nanosheets is reported. The orientational ordering is achieved by a rapid evaporation of mixed solvents during the electrode fabrication process. Compared with conventional drop-cast electrodes, which exhibit a random arrangement of the nanosheets and obvious decrease of rate performance with increasing thickness, the electrode based on the vertically aligned nanosheets is able to retain the original high rate capability even at high mass loadings and electrode thickness. Furthermore, combined electrochemical and structural characterization reveals the electrode composed of orientation-controlled nanosheets to possess lower charge-transfer resistances, leading to more complete phase transformation in the active material.

25 ENERGY STORAGE↗