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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Insulator Nanostructure Desorption Ionization Mass Spectrometry

Surface-assisted laser desorption ionization (SALDI) is an approach for gas-phase ion generation for mass spectrometry using laser excitation on typically conductive or semiconductive nanostructures. Here, we introduce insulator nanostructure desorption ionization mass spectrometry (INDI-MS), a nanostructured polymer substrate for SALDI-MS analysis of small molecules and peptides. INDI-MS surfaces are produced through the self-assembly of a perfluoroalkyl silsesquioxane nanostructures in a single chemical vapor deposition silanization-step. We find that surfaces formed from the perfluorooctyltrichlorosilane monomer assemble semielliptical features with a 10 nm height, diameters between 10 and 50 nm, and have attomole–femtomole sensitivities for selected analytes. Surfaces prepared with silanes that either lack the trichloro or perfluoro groups, lack sensitivity. Further, we demonstrate that hydrophobic INDI regions can be micropatterned onto hydrophilic surfaces to perform on-chip self-desalting in an array format.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Sulfated glycopeptide nanostructures for multipotent protein activation

Biological systems have evolved to utilize numerous proteins with capacity to bind polysaccharides for the purpose of optimizing their function. A well-known subset of these proteins with binding domains for the highly diverse sulfated polysaccharides are important growth factors involved in biological development and tissue repair. Here, we report on supramolecular sulfated glycopeptide nanostructures, which display a trisulfated monosaccharide on their surfaces and bind five critical proteins with very different polysaccharide binding domains. Binding does not disrupt the filamentous shape of the nanostructures or their internal β-sheet backbone, but must involve accessible adaptive configurations to interact with such different proteins. The glycopeptide nanostructures amplified signaling of bone morphogenetic protein 2 significantly more than the natural sulfated polysaccharide heparin, and promoted regeneration of bone in the spine with a protein dose that is 100-fold lower than expected. These super-bioactive nanostructures may enable many therapies in the horizon involving proteins.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Shape controlled Sn doped ZnO nanostructures for tunable optical emission and transport properties

Pure and Sn doped ZnO nanostructures have been grown on SiO{sub 2}/Si substrates by vapor-solid technique without using any catalysts. It has been found that the morphology of the nanostructures depend strongly on the growth temperature and doping concentration. By proper tuning of the growth temperature, morphology of pure ZnO can be changed from tetrapods to multipods. On the other hand, by varying the doping concentration of Sn in ZnO, the morphology can be tuned from tetrapods to flower-like multipods to nanowires. X-ray diffraction pattern reveals that the nanostructures have a preferred (0002) growth orientation, and they are tensile strained with the increase of Sn doping in ZnO. Temperature-dependent photoluminescence characteristics of these nanostructures have been investigated in the range from 10 to 300 K. Pure ZnO tetrapods exhibited less defect state emissions than that of pure ZnO multipods. The defect emission is reduced with low concentration of Sn doping, but again increases at higher concentration of doping because of increased defects. Transport properties of pure and Sn doped ZnO tetrapods have been studied using complex-plane impedance spectroscopy. The contribution from the arms and junctions of a tetrapod could be distinguished. Sn doped ZnO samples showed lower conductivity but higher relaxation time than that of pure ZnO tetrapods.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Hetero-nanostructured materials for high-power lithium ion batteries

The development of high technology electrical devices increased the importance of higher power density or higher capacity at high current density. Especially, rapid charge/discharge issues remain problematic for electric vehicle commercialization. After extensive investigation, researchers introduced hetero-nanostructured materials to the field of lithium ion batteries (LIBs), aiming to enhance the power density or improve the capacity at high current density and life cycle capability. Hetero-nanostructured materials consist of current collectors and directly attached active nanomaterials. Carbon, carbon nanotube (CNT), graphene, Nickel (Ni), Copper (Cu) and Aluminum (Al) were used for current collector, aiming to improve the electron transfer and the cyclability, due to high electrical conductivity and superior buffering effects. Also, Hetero-nanostructure can produce a favorable lithium diffusion condition by creating a lithium diffusion pathway. This article presents an explanation of important factors for high power density or high capacity at high current density. It summarizes the capacity of electrode materials at high current density, including structural descriptions and material types.

Lee, Jaewon↗
DOE OSTI2021

Control of Peptide Amphiphile Supramolecular Nanostructures by Isosteric Replacements

Supramolecular nanostructures with tunable properties can have applications in medicine, pharmacy, and biotechnology. In this work, we show that the self-assembly behavior of peptide amphiphiles (PAs) can be effectively tuned by replacing the carboxylic acids exposed to the aqueous media with isosteres, functionalities that share key physical or chemical properties with another chemical group. Transmission electron microscopy, atomic force microscopy, and small-angle X-ray scattering studies indicated that the nanostructure’s morphologies are responsive to the ionization states of the side chains, which are related to their pK a values. Circular dichroism studies revealed the effect of the isosteres on the internal arrangement of the nanostructures. The interactions between diverse surfaces and the nanostructures and the effect of salt concentration and temperature were assessed to further understand the properties of these self-assembled systems. These results indicate that isosteric replacements allow the pH control of supramolecular morphology by manipulating the pK a of the charged groups located on the nanostructure’s surface. Theoretical studies were performed to understand the morphological transitions that the nanostructures underwent in response to pH changes, suggesting that the transitions result from alterations in the Coulomb forces between PA molecules. Furthermore, this work provides a strategy for designing biomaterials that can maintain or change behaviors based on the pH differences found within cells and tissues.

36 MATERIALS SCIENCE↗
DOE OSTI2014

DROPWISE CONDENSATION ON MICRO- AND NANOSTRUCTURED SURFACES

In this review we cover recent developments in the area of surface-enhanced dropwise condensation against the background of earlier work. The development of fabrication techniques to create surface structures at the micro-and nanoscale using both bottom-up and top-down approaches has led to increased study of complex interfacial phenomena. In the heat transfer community, researchers have been extensively exploring the use of advanced surface structuring techniques to enhance phase-change heat transfer processes. In particular, the field of vapor-to-liquid condensation and especially that of water condensation has experienced a renaissance due to the promise of further optimizing this process at the micro-and nanoscale by exploiting advances in surface engineering developed over the last several decades.

Enright, R↗
DOE OSTI2014

Intrinsic Nanostructure in Zr 2-x Fe 4 Si 16-y (x=0.81, y=6.06)

We present a study of the crystal structure and physical properties of single crystals of a new Fe-based ternary compound, Zr 2-x Fe 4 Si 16-y (x=0.81,y=6.06). Zr 1.19 Fe 4 Si 9.94 is a layered compound, where stoichiometric β-FeSi 2 -derived slabs are separated by Zr-Si planes with substantial numbers of vacancies. High resolution transmission electron microscopy (HRTEM) experiments show that these Zr-Si layers consist of 3.5nm domains where the Zrand Si vacancies are ordered within a supercell sixteen times the volume of the stoichiometric cell. Within these domains, the occupancies of the Zr and Si sites obey symmetry rules that permit only certain compositions, none of which by themselves reproduce the average composition found in x-ray diffraction experiments. Magnetic susceptibility and magnetization measurements reveal a small but appreciable number of magnetic moments that remain freely fluctuating to 1.8K, while neutron diffraction confirms the absence of bulk magnetic order with a moment of 0.2μB or larger down to 1.5K. Electrical resistivity measurements find that Zr 1.19 Fe 4 Si 9.94 is metallic, and the modest value of the Sommerfeld coefficient of the specific heat γ = C/T suggests that quasi-particle masses are not particularly strongly enhanced. The onset of superconductivity at T c ≃ 6K results in a partial resistive transition and a small Meissner signal, although a bulk-like transition is found in the specific heat. Sharp peaks in the ac susceptibility signal the interplay of the normal skin depth and the London penetration depth, typical of a system in which nano-sized superconducting grains are separated by a on-superconducting host. Ultra low field differential magnetic susceptibility measurements reveal the presence of a surprisingly large number of trace magnetic and superconducting phases, suggesting that the Zr-Fe-Si ternary system could be a potentially rich source of new bulk superconductor.

36 MATERIALS SCIENCE↗
DOE OSTI2017

A Tunable 3D Nanostructured Conductive Gel Framework Electrode for High-Performance Lithium Ion Batteries

This study develops a tunable 3D nanostructured conductive gel framework as both binder and conductive framework for lithium ion batteries. A 3D nanostructured gel framework with continuous electron pathways can provide hierarchical pores for ion transport and form uniform coatings on each active particle against aggregation. The hybrid gel electrodes based on a polypyrrole gel framework and Fe3O4 nanoparticles as a model system in this study demonstrate the best rate performance, the highest achieved mass ratio of active materials, and the highest achieved specific capacities when considering total mass, compared to current literature. This 3D nanostructured gelbased framework represents a powerful platform for various electrochemically active materials to enable the next-generation high-energy batteries.

25 ENERGY STORAGE↗
DOE OSTI2017

Comprehensive Enhancement of Nanostructured Lithium-Ion Battery Cathode Materials via Conformal Graphene Dispersion

Efficient energy storage systems based on lithium-ion batteries represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Nanostructured electrode materials present compelling opportunities for high-performance lithium-ion batteries, but inherent problems related to the high surface area to volume ratios at the nanometer-scale have impeded their adoption for commercial applications. Here, we demonstrate a materials and processing platform that realizes high-performance nanostructured lithium manganese oxide (nano-LMO) spinel cathodes with conformal graphene coatings as a conductive additive. The resulting nanostructured composite cathodes concurrently resolve multiple problems that have plagued nanoparticle-based lithium-ion battery electrodes including low packing density, high additive content, and poor cycling stability. Moreover, this strategy enhances the intrinsic advantages of nano-LMO, resulting in extraordinary rate capability and low temperature performance. With 75% capacity retention at a 20C cycling rate at room temperature and nearly full capacity retention at -20 degrees C, this work advances lithium-ion battery technology into unprecedented regimes of operation.

25 ENERGY STORAGE↗
DOE OSTI2021

Supramolecular Interactions and Morphology of Self-Assembling Peptide Amphiphile Nanostructures

The morphology of supramolecular peptide nanostructures is difficult to predict given their complex energy landscapes. We investigated peptide amphiphiles containing β-sheet forming domains that form twisted nanoribbons in water. We explained the morphology based on a balance between the energetically favorable packing of molecules in the center of the nanostructures, the unfavorable packing at the edges, and the deformations due to packing of twisted β-sheets. We find that morphological polydispersity of PA nanostructures is determined by peptide sequences, and the twisting of their internal β-sheets. Here, we also observed a change in the supramolecular chirality of the nanostructures as the peptide sequence was modified, although only amino acids with l-configuration were used. Upon increasing charge repulsion between molecules, we observed a change in morphology to long cylinders and then rodlike fragments and spherical micelles. Understanding the self-assembly mechanisms of peptide amphiphiles into nanostructures should be useful to optimize their well-known functions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Symmetric nanostructuring and plasmonic excitation of gold nanostructures by femtosecond Laguerre – Gaussian laser beams

Femtosecond low-energy Laguerre – Gaussian pulses of tightly focused visible laser radiation were employed for single-pulse ablative nanostructuring of a 50-nm thick gold film. Similar pulses of lower energy were employed for the efficient plasmonic photoluminescence excitation of a rhodamine 6G dye monolayer in the fabricated nanostructures. The consistency between the shape and polarisation symmetries of the low-energy laser beam, on the one hand, and the gold nanostructures produced by the same beam at a high radiation energy, on the other hand, opens the way to consistent nanostructuring and surface-enhanced analytical spectroscopy with the use of nanostructures. (interaction of laser radiation with matter)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗