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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Hydrodynamic and frictional modulation of deformations in switchable colloidal crystallites

Displacive transformations in colloidal crystals may offer a pathway for increasing the diversity of accessible configurations without the need to engineer particle shape or interaction complexity. To date, binary crystals composed of spherically symmetric particles at specific size ratios have been formed that exhibit floppiness and facile routes for transformation into more rigid structures that are otherwise not accessible by direct nucleation and growth. There is evidence that such transformations, at least at the micrometer scale, are kinetically influenced by concomitant solvent motion that effectively induces hydrodynamic correlations between particles. Here, we study quantitatively the impact of such interactions on the transformation of binary bcc-CsCl analog crystals into close-packed configurations. We first employ principal-component analysis to stratify the explorations of a bcc-CsCl crystallite into orthogonal directions according to displacement. We then compute diffusion coefficients along the different directions using several dynamical models and find that hydrodynamic correlations, depending on their range, can either enhance or dampen collective particle motions. These two distinct effects work synergistically to bias crystallite deformations toward a subset of the available outcomes.

42 ENGINEERING↗
DOE OSTI2026

Observation of Switchable Chiral Magnons in an Altermagnet

Chiral magnons, the quanta of handed spin waves, transport spin angular momentum without energy loss due to Joule heating. Here, the recently discovered altermagnets were proposed to host chiral magnons arising from a nonrelativistic exchange mechanism, similar to that in ferromagnets but without net magnetization, offering a stray-field-free platform for efficient magnon spin-current manipulation. In this Letter, we directly observed chiral magnons in the altermagnetic prototype MnTe using polarized inelastic neutron scattering. Furthermore, the magnon chirality was found to be reversibly switched by magnetic-field control, establishing a robust foundation for functional altermagnetic magnonics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Origins of anisotropic transport in the electrically switchable antiferromagnet Fe 1/3 NbS 2

Recent experiments on the antiferromagnetic intercalated transition metal dichalcogenide Fe 1/3 NbS 2 have demonstrated reversible resistivity switching by application of orthogonal current pulses below its magnetic ordering temperature, making Fe 1/3 NbS 2 promising for spintronics applications. Here, we perform density functional theory calculations with Hubbard U corrections of the magnetic order, electronic structure, and transport properties of crystalline Fe 1/3 NbS 2 , clarifying the origin of the different resistance states. The two experimentally proposed antiferromagnetic ground states, corresponding to in-plane stripe and zigzag ordering, are computed to be nearly degenerate. In-plane cross sections of the calculated Fermi surfaces are anisotropic for both magnetic orderings, with the degree of anisotropy sensitive to the Hubbard U value. The in-plane resistance, computed within the Kubo linear response formalism using a constant relaxation time approximation, is also anisotropic, supporting a hypothesis that the current-induced resistance changes are due to a repopulating of antiferromagnetic domains. Our calculations indicate that the transport anisotropy of Fe 1/3 NbS 2 in the zigzag phase is reduced relative to stripe, consistent with the relative magnitudes of resistivity changes in experiment. Finally, our calculations reveal the likely directionality of the current-domain response, specifically, which domains are energetically stabilized for a given current direction.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Strain-switchable field-induced superconductivity

Field-induced superconductivity is a rare phenomenon where an applied magnetic field enhances or induces superconductivity. Here, we use applied stress as a control switch between a field-tunable superconducting state and a robust non–field-tunable state. This marks the first demonstration of a strain-tunable superconducting spin valve with infinite magnetoresistance. We combine tunable uniaxial stress and applied magnetic field on the ferromagnetic superconductor Eu(Fe 0.88 Co 0.12 ) 2 As 2 to shift the field-induced zero-resistance temperature between 4 K and a record-high value of 10 K. We use x-ray diffraction and spectroscopy measurements under stress and field to reveal that strain tuning of the nematic order and field tuning of the ferromagnetism act as independent control parameters of the superconductivity. Combining comprehensive measurements with DFT calculations, we propose that field-induced superconductivity arises from a novel mechanism, namely, the uniquely dominant effect of the Eu dipolar field when the exchange field splitting is nearly zero.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Switchable client specificity in a dual functional chaperone coordinates light-harvesting complex biogenesis

The proper assembly of light-harvesting complexes (LHCs) is critical for photosynthesis and requires the biogenesis of light-harvesting chlorophylla,b-binding proteins (LHCPs) to be coordinated with chlorophyll (Chl) biosynthesis. The mechanism underlying this coordination is not well understood. Here, we show that a conserved molecular chaperone, chloroplast signal recognition particle 43-kDa protein (cpSRP43), provides a molecular thermostat that helps maintain this coordination. cpSRP43 undergoes a conformational rearrangement between a well-folded closed state and a partially disordered open state. Closed cpSRP43 is dedicated to the biogenesis of LHCPs, whereas open cpSRP43 protects multiple Chl biosynthesis enzymes from heat-induced destabilization. Rising temperature shifts cpSRP43 to the open state, enabling it to protect heat-destabilized Chl biosynthesis enzymes. Our results reveal the molecular basis of a posttranslational mechanism for the thermoadaptation of LHC biogenesis. They also demonstrate how an adenosine triphosphate–independent chaperone uses conformational dynamics to switch its activity and client selectivity, thereby adapting to different proteostatic demands under shifting environmental conditions.

Science & Technology - Other Topics↗
DOE OSTI2021

Simultaneous Capture and Conversion of CO 2 to Methanol via a Switchable Ionic Liquid and Low-Temperature Metal Catalyst (CRADA 449)

Advance development of the Integrated (Carbon Dioxide) CO 2 Capture and Conversion to Methanol (ICCCM) process, which is based on PNNL’s proprietary Carbon Dioxide Binding Organic Liquids (CO 2 BOLs) capture solvent technology for separating the CO 2 from dilute streams. Design, fabricate, and demonstrate a bench-scale ICCCM prototype for the continuous flow combined capture and catalytic conversion of CO 2 into methanol and assess viability for commercialization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Switchable rocker arm

A rocker arm includes an outer arm defining a lock pin bore which is centered about a lock pin bore axis and an inner arm which selectively pivots relative to the outer arm about a pivot axis which is parallel to the lock pin bore axis. The inner arm includes a protrusion which defines an inner arm stop surface which is planar. A lock pin is disposed within the lock pin bore, the lock pin having a lock pin slot extending there into and also having a lock pin stop surface which is planar. The lock pin is displaced within the lock pin bore between a coupled position in which the lock pin stop surface is aligned with the inner arm stop surface and a decoupled position in which the lock pin slot is aligned with the protrusion.

42 ENGINEERING↗
DOE OSTI2020

Switchable rocker arm

A rocker arm includes an outer arm and an inner arm which selectively pivots relative to the outer arm. The rocker arm also includes a lock pin which is displaced along a lock pin axis between a coupled position and a decoupled position. The rocker arm also includes a linkage and a linkage guide which guides the linkage along a linkage axis. One surface of the linkage engages an actuator while another surface of the linkage engages the lock pin such that the linkage translates motion from the actuator to motion of the lock pin.

42 ENGINEERING↗
DOE OSTI2021

Designed proteins for pH switchable antibody purification

Modified Fc-binding domain polypeptides or polypeptides including one or more modified Fc-binding domains are provided. In some examples, a modified Fc-binding domain includes or consists of the amino acid sequence of any one of SEQ ID NOs: 4, 6, or 8. Nucleic acids encoding the modified Fc-binding domains or polypeptides including one or more of the modified Fc-binding domains are also provided. In some embodiments, the nucleic acids are included in a vector and may be operably linked to a promoter. Methods for purifying a polypeptide including one or more Fc regions are also provided. Kits and reagents including the modified Fc-binding domain polypeptides or polypeptides including one or more modified Fc-binding domains are provided. In some examples, the modified Fc-binding domain polypeptides or polypeptides including one or more modified Fc-binding domains are linked to a solid support.

Jha, Roshan Kumar↗
DOE OSTI2021

Switchable ionic liquids for biomass pretreatment and enzymatic hydrolysis

In one aspect, the present invention provides a method for preparing a sugar composition. The method includes: forming a mixture including polysaccharide biomass and an ionic liquid solution, wherein the ionic liquid solution contains water and an ionic liquid, and wherein the ionic liquid contains a dicarboxylic acid anion and a cation. The pH of the mixture is greater than or equal to about 10, and the molar ratio of the dicarboxylic acid anion to the cation is at least about 1:2. The method further includes: maintaining the mixture under conditions sufficient to dissolve at least a portion of the polysaccharide present in the polysaccharide biomass; reducing the pH of the mixture containing the dissolved polysaccharide to at least about 7; adding at least one glycoside hydrolase to the mixture having the reduced pH.

Liszka, Michael↗
DOE OSTI2023

Switchable photovoltaic devices

The present disclosure relates to a composition that includes a scaffold having an internal space and a mixture positioned within the space, where the mixture includes a first phase having a metal halide perovskite and a second phase including at least one of a perovskite precursor and/or a switching molecule, the composition is capable of reversibly switching between a first state having at least one of a first transparency and/or a first color and a second state having at least one of a second transparency and/or a second color.

Wheeler, Lance Michael↗
DOE OSTI2023

Switchable system for high-salinity brine desalination and fractional precipitation

A saline feed stream flows into a liquid-liquid extraction system; and a volatile organic solvent flows through a main compressor. The compressed volatile organic solvent then flows through a solvent regenerator, which can be a heat exchanger or a combination of a vaporization device and a condenser, to cool the volatile organic solvent. The cooled volatile organic solvent in liquid phase then flows into the liquid-liquid extraction system, where the saline feed stream contacts the volatile organic solvent to selectively extract water from the saline feed stream into the volatile organic solvent, producing a concentrated brine and an organic-rich mixture of water and the volatile organic solvent. The organic-rich mixture flows from the liquid-liquid extraction system into the solvent regenerator, where the organic-rich mixture is heated to produce an organic-rich vapor and desalinated water; and the organic-rich vapor is recycled as volatile organic solvent back into the liquid-liquid extraction system.

Wilson, Aaron D.↗
DOE OSTI2025

Multifunctional Polar 2D Lead Iodide Perovskites Exhibiting Persistent Spin Texture

Ferroelectric Rashba semiconductors are a rare class of multifunctional materials promising for spin–orbitronics due to the possibility of electrically switchable spin textures. Hybrid organic–inorganic metal halide perovskites offer exceptional tunability that can be harnessed to target noncentrosymmetry; however, the complex interactions between organic and inorganic components are not rationally understood. Here, we use an asymmetric spacer cation with a strong molecular dipole moment (2-fluorobenzylammonium, 2FBZ) and increase the intrinsic quantum well thickness to n > 1 to synthesize three new polar 2D lead iodide perovskites (2FBZ) 2 (A) n-1 Pb n I 3n+1 with A = methylammonium (MA) or formamidinium (FA) and n = 2, 3. Single-crystal structure analysis reveals the C 2v symmetry of these crystal structures and substantial structural distortions, which enable Rashba and Dresselhaus band splitting and persistent spin texture, confirmed by DFT calculations. Measurements of the resulting symmetry-dependent properties, such as second harmonic generation, switchable photovoltaic effect, ferroelectric polarization, and low temperature photoluminescence show switchable ferroelectric semiconducting properties. Furthermore, these results introduce a general chemical design strategy toward polar symmetry by exploiting the complex interplay between asymmetric spacer cations and A-site cations in quasi-2D (n > 1) halide perovskites to realize new classes of multifunctional materials for future spin–orbitronic applications.

Cations↗