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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

A high-transparency, micro-patternable chip for X-ray diffraction analysis of microcrystals under native growth conditions

A highly X-ray-transparent, silicon nitride-based device has been designed and fabricated to harvest protein microcrystals for high-resolution X-ray diffraction data collection using microfocus beamlines and XFELs. Microcrystals present a significant impediment to the determination of macromolecular structures by X-ray diffraction methods. Although microfocus synchrotron beamlines and X-ray free-electron lasers (XFELs) can enable the collection of interpretable diffraction data from microcrystals, there is a need for efficient methods of harvesting small volumes (<2 µl) of microcrystals grown under common laboratory formats and delivering them to an X-ray beam source under native growth conditions. One approach that shows promise in overcoming the challenges intrinsic to microcrystal analysis is to pair so-called ‘fixed-target’ sample-delivery devices with microbeam-based X-ray diffraction methods. However, to record weak diffraction patterns it is necessary to fabricate devices from X-ray-transparent materials that minimize background scattering. Presented here is the design of a new micro-diffraction device consisting of three layers fabricated from silicon nitride, photoresist and polyimide film. The chip features low X-ray scattering and X-ray absorption properties, and uses a customizable blend of hydrophobic and hydrophilic surface patterns to help localize microcrystals to defined regions. Microcrystals in their native growth conditions can be loaded into the chips with a standard pipette, allowing data collection at room temperature. Diffraction data collected from hen egg-white lysozyme microcrystals (10–15 µm) loaded into the chips yielded a complete, high-resolution (<1.6 Å) data set sufficient to determine a high-quality structure by molecular replacement. The features of the chip allow the rapid and user-friendly analysis of microcrystals grown under virtually any laboratory format at microfocus synchrotron beamlines and XFELs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Capture and X-ray diffraction studies of protein microcrystals in a microfluidic trap array

A microfluidic platform has been developed for the capture and X-ray analysis of protein microcrystals, affording a means to improve the efficiency of XFEL and synchrotron experiments. X-ray free-electron lasers (XFELs) promise to enable the collection of interpretable diffraction data from samples that are refractory to data collection at synchrotron sources. At present, however, more efficient sample-delivery methods that minimize the consumption of microcrystalline material are needed to allow the application of XFEL sources to a wide range of challenging structural targets of biological importance. Here, a microfluidic chip is presented in which microcrystals can be captured at fixed, addressable points in a trap array from a small volume (<10 µl) of a pre-existing slurry grown off-chip. The device can be mounted on a standard goniostat for conducting diffraction experiments at room temperature without the need for flash-cooling. Proof-of-principle tests with a model system (hen egg-white lysozyme) demonstrated the high efficiency of the microfluidic approach for crystal harvesting, permitting the collection of sufficient data from only 265 single-crystal still images to permit determination and refinement of the structure of the protein. This work shows that microfluidic capture devices can be readily used to facilitate data collection from protein microcrystals grown in traditional laboratory formats, enabling analysis when cryopreservation is problematic or when only small numbers of crystals are available. Such microfluidic capture devices may also be useful for data collection at synchrotron sources.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Serial femtosecond X-ray diffraction of enveloped virus microcrystals

Serial femtosecond crystallography (SFX) using X-ray free-electron lasers has produced high-resolution, room temperature, time-resolved protein structures. We report preliminary SFX of Sindbis virus, an enveloped icosahedral RNA virus with ~700 Å diameter. Microcrystals delivered in viscous agarose medium diffracted to ~40 Å resolution. Small-angle diffuse X-ray scattering overlaid Bragg peaks and analysis suggests this results from molecular transforms of individual particles. Viral proteins undergo structural changes during entry and infection, which could, in principle, be studied with SFX. This is a pertinent step toward determining room temperature structures from virus microcrystals that may enable time-resolved studies of enveloped viruses.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Chloride Flux Growth of Idiomorphic AWO 4 (A = Sr, Ba) Single Microcrystals

Scheelite-type divalent metal tungstate materials (AWO 4 ) have been studied for various applications due to their attractive mechanical and chemical properties. Preparation of the shape-controlled AWO 4 crystals with high crystallinity is one of the most effective approaches for further exploring and improving their properties. In this study, highly crystalline SrWO 4 and BaWO 4 microcrystals with different morphologies were grown by using a chloride flux growth technique. To investigate the effect of growth conditions on SrWO 4 and BaWO 4 crystals, NaCl and KCl were used as a flux, and the solute concentration was adjusted in the range of 5-50 mol %. The difference in the flux cation species (Na + and K + ) mainly affected the crystal size. In accordance with increasing the solute concentration, the dominant crystal shape of SrWO 4 and BaWO 4 varied as follows: whisker (a rod- or wire-like morphology with a large aspect ratio) → platelet → well/less-faceted polyhedron. Additionally, according to scanning electron microscopy and transmission electron microscopy results, a dendritic morphological transformation from AWO4 whisker to platelet during crystal growth has been proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Visualizing Overall Water Splitting on Single Microcrystals of Phosphorus-Doped BiVO 4 by Photo-SECM

Particulate bismuth vanadate (BiVO4) has attracted considerable interest as a promising photo(electro)catalyst for visible-light-driven water oxidation, however, overall water splitting (OWS) has been difficult to attain because its conduction band is too positive for efficient hydrogen evolution. Using photo-scanning electrochemical microscopy (photo-SECM) with a chemically modified nanotip, we visualized for the first time the OWS at a single truncated bipyramidal microcrystal of phosphorus-doped BiVO 4 . The tip simultaneously served as a light guide to illuminate the photocatalyst and as an electrochemical nanoprobe to observe and quantitatively measure local oxygen and hydrogen fluxes. The obtained current patterns for both O 2 and H 2 agree well with the accumulation of photogenerated holes and electrons on {010} basal and {110} lateral facets, respectively. Furthermore, the developed experimental approach is an important step towards nanoelectrochemical mapping of the activity of photocatalyst particles at the sub-facet level.

bismuth vanadate↗
DOE OSTI2016

Three-dimensional reconstruction of the size and shape of protein microcrystals using Bragg coherent diffractive imaging

Three-dimensional imaging of protein crystals during X-ray diffraction experiments opens up a range of possibilities for optimising crystal quality and gaining new insights into the fundamental processes that drive radiation damage. Obtaining this information at the appropriate lengthscales however is extremely challenging. One approach that has been recently demonstrated as a promising avenue for charactering the size and shape of protein crystals at nanometre lengthscales is Bragg Coherent Diffractive Imaging (BCDI). BCDI is a recently developed technique that is able to recover the phase of the continuous diffraction intensity signal around individual Bragg peaks. When data is collected at multiple points on a rocking curve a Reciprocal Space Map (RSM) can be assembled and then inverted using BCDI to obtain a three-dimensional image of the crystal. The first demonstration of two-dimensional BCDI of protein crystals was reported by Boutet at al., recently this work was extended to the study of radiation damage of micron-sized crystals. Here we present the first three-dimensional reconstructions of a Lysozyme protein crystal using BDI. The results are validated against RSM and TEM data and have implications for both radiation damage studies and for developing new approaches to structure retrieval from micron-sized protein crystals.

Bragg coherent diffractive imaging↗
DOE OSTI2011

Morphology evolution from thin-hexapod to aggregated sphere of Cu{sub 2}O microcrystals

Highlights: {yields} In this work we report the first simple morphology-controlled synthesis for various morphologies of Cu{sub 2}O microcrystals. {yields} We synthesized the Cu{sub 2}O microcrystals using a conventional microwave oven only for 3 min. {yields} We find that the amount of glucose and the microwave irradiation time play important roles in controlling the morphology of Cu{sub 2}O microcrystals. -- Abstract: A range of morphologies of Cu{sub 2}O microcrystals, such as thin-hexapod, thick-hexapod, truncated hexapod, truncated octahedron, cuboctahedron, and aggregated sphere were prepared by the reduction reaction from the mixed solution of CuCl{sub 2}, NaOH, glucose, and poly(ethylene) glycol. Monodispersed and well-crystallized Cu{sub 2}O microcrystals were prepared for only a few minutes using a conventional microwave oven. The amount of glucose and the microwave irradiation time play important roles in controlling the morphology of the Cu{sub 2}O microcrystals. The morphology of the Cu{sub 2}O microcrystals was changed from thin-hexapod to aggregated sphere by the glucose concentration. The morphology of Cu{sub 2}O microcrystals was changed from thick-hexapod to octahedron by increasing the microwave irradiation time. The crystal growth mechanism and morphology evolution of Cu{sub 2}O microcrystals are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2020

PyMDA : microcrystal data assembly using Python

The recent developments at microdiffraction X-ray beamlines are making microcrystals of macromolecules appealing subjects for routine structural analysis. Microcrystal diffraction data collected at synchrotron microdiffraction beamlines may be radiation damaged with incomplete data per microcrystal and with unit-cell variations. A multi-stage data assembly method has previously been designed for microcrystal synchrotron crystallography. Here the strategy has been implemented as a Python program for microcrystal data assembly ( PyMDA ). PyMDA optimizes microcrystal data quality including weak anomalous signals through iterative crystal and frame rejections. Beyond microcrystals, PyMDA may be applicable for assembling data sets from larger crystals for improved data quality.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Sample manipulation and data assembly for robust microcrystal synchrotron crystallography

With the recent developments in microcrystal handling, synchrotron microdiffraction beamline instrumentation and data analysis, microcrystal crystallography with crystal sizes of less than 10 µm is appealing at synchrotrons. However, challenges remain in sample manipulation and data assembly for robust microcrystal synchrotron crystallography. Here, the development of micro-sized polyimide well-mounts for the manipulation of microcrystals of a few micrometres in size and the implementation of a robust data-analysis method for the assembly of rotational microdiffraction data sets from many microcrystals are described. The method demonstrates that microcrystals may be routinely utilized for the acquisition and assembly of complete data sets from synchrotron microdiffraction beamlines.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Low-temperature hydrothermal synthesis of BiFeO{sub 3} microcrystals and their visible-light photocatalytic activity

Highlights: ► Urea-assisted hydrothermal synthesis of pure BiFeO{sub 3} at 120 °C was reported. ► Possible formation mechanism of pure phase BiFeO{sub 3} at low temperature was illuminated. ► BiFeO{sub 3} microcrystals exhibited efficient visible-light photocatalytic activity. -- Abstract: Pure BiFeO{sub 3} (BFO) microcrystals were synthesized at the temperature as low as 120 °C via a urea-assisted hydrothermal process. The crystal structure, morphology and photocatalytic property of BFO microcrystals were investigated. The analysis reveals that the hydrolysis of urea in the hydrothermal process plays a key role in the synthesis of pure phase BFO microcrystals. FE-SEM and TEM results show that these BFO microcrystals present a nearly spherical microstructure, and specially exhibit superstructures consisting of large amounts of small particles with the size of 100–150 nm by further observation. Moreover, these BFO microcrystals exhibit efficient photocatalytic activity under visible-light irradiation, suggesting their promising applications as photocatalysts and related fields.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Controlled synthesis of different morphologies of TiB{sub 2} microcrystals by aluminum melt reaction method

Highlights: ► TiB{sub 2} microcrystals with different morphologies were synthesized. ► The growth of TiB{sub 2} is controlled by two-dimensional nucleation in Al melt. ► The growth of the hierarchical TiB{sub 2} microcrystals is controlled by two steps. - Abstract: TiB{sub 2} microcrystals with different morphologies, including hexagonal plate-like, tower-like and dendritic, were fabricated by aluminum melt reaction method in this study. The growth mechanisms of these microcrystals are also discussed based on the fundamental crystal growth theories. It is found that the growth of TiB{sub 2} is controlled by two-dimensional nucleation in aluminum melt. If the atomic concentration, reaction rate and atomic diffusion rate in the melt are high, TiB{sub 2} microcrystals exhibit hierarchical tower-like and dendritic morphologies. Otherwise, the single crystal of hexagonal plate-like morphology is obtained. The growth of the hierarchical TiB{sub 2} microcrystals is controlled by two steps, intermittent two-dimensional nucleation and continuous lateral spreading of layers on the growth faces.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Controllable synthesis, shape evolution, and luminescence properties of uniform and well-dispersed NaEuF{sub 4} microcrystals through hydrothermal route

Graphical abstract: Sodium europium fluorides NaEuF{sub 4} microcrystals have been prepared via a facile hydrothermal route. The possible growth mechanism and the luminescent properties of the as-prepared microcrystals have been discussed. - Highlights: • Sodium europium fluorides NaEuF{sub 4} microspheres were prepared by a facile hydrothermal route. • The as-prepared samples NaEuF{sub 4} and EuF{sub 3} exhibit respective red or orange-red emissions. • These finding may find potential applications in the fields of color display, UV laser and biomedicine. - Abstract: Sodium europium fluorides NaEuF{sub 4} microcrystals with uniform and well-dispersed shapes and dimensions have been prepared via a facile hydrothermal route using Na{sub 3}Cit as the chelating ligand and shape modifier. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), energy-dispersive X-ray (EDX) and photoluminescence spectra (PL) were taken to characterize the samples. A series of controlled experiments reveal that the trisodium citrate (Na{sub 3}Cit) content, pH value of the initial solution, and reaction time have an indispensable role on the phase, size, and morphology of the as-prepared microcrystals. Based on the experimental results, the possible growth mechanism of the microcrystals prepared under different conditions was proposed. Moreover, we systematically investigated the luminescent properties of the as-prepared microcrystals with different morphologies obtained under different amounts of Na{sub 3}Cit, which have potential application in the fields of color display, UV laser and biomedicine.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Controlling the Temperature and Speed of the Phase Transition of VO 2 Microcrystals

Here, we investigated the control of two important parameters of vanadium dioxide (VO 2 ) microcrystals, the phase transition temperature and speed, by varying microcrystal width. By using the reflectivity change between insulating and metallic phases, phase transition temperature is measured by optical microscopy. As the width of square cylinder-shaped microcrystals decreases from ~70 to ~1 μm, the phase transition temperature (67 °C for bulk) varied as much as 26.1 °C (19.7 °C) during heating (cooling). In addition, the propagation speed of phase boundary in the microcrystal, i.e., phase transition speed, is monitored at the onset of phase transition by using the high-speed resistance measurement. The phase transition speed increases from 4.6 × 10 2 to 1.7 × 10 4 μm/s as the width decreases from ~50 to ~2 μm. While the statistical description for a heterogeneous nucleation process explains the size dependence on phase transition temperature of VO 2 , the increase of effective thermal exchange process is responsible for the enhancement of phase transition speed of small VO 2 microcrystals. These findings not only enhance the understanding of VO 2 intrinsic properties but also contribute to the development of innovative electronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Synchrotron microcrystal native-SAD phasing at a low energy

De novo structural evaluation of native biomolecules from single-wavelength anomalous diffraction (SAD) is a challenge because of the weakness of the anomalous scattering. The anomalous scattering from relevant native elements – primarily sulfur in proteins and phosphorus in nucleic acids – increases as the X-ray energy decreases toward their K -edge transitions. Thus, measurements at a lowered X-ray energy are promising for making native SAD routine and robust. For microcrystals with sizes less than 10 µm, native-SAD phasing at synchrotron microdiffraction beamlines is even more challenging because of difficulties in sample manipulation, diffraction data collection and data analysis. Native-SAD analysis from microcrystals by using X-ray free-electron lasers has been demonstrated but has required use of thousands of thousands of microcrystals to achieve the necessary accuracy. Here it is shown that by exploitation of anomalous microdiffraction signals obtained at 5 keV, by the use of polyimide wellmounts, and by an iterative crystal and frame-rejection method, microcrystal native-SAD phasing is possible from as few as about 1 200 crystals. Our results show the utility of low-energy native-SAD phasing with microcrystals at synchrotron microdiffraction beamlines.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Data analysis for synchrotron microcrystal native-SAD phasing

De novo structural evaluation of native biomolecules from single-wavelength anomalous diffraction (SAD) is a challenge because of the weakness of the anomalous scattering. For microcrystals with sizes less than 10 μm, native-SAD phasing at synchrotron microdiffraction beamlines is even more challenging due to difficulties in sample manipulation, diffraction data collection and data analysis. Native-SAD analysis from microcrystals by using X-ray free electron lasers has been demonstrated but has required use of thousands of thousands of microcrystals to achieve the necessary accuracy. Here we show that by exploitation of anomalous microdiffraction signals at a synchrotron beamline, by the use of polyimide wellmounts, and by an iterative crystal and frame rejection method, optimized data may be acquired and assembled which allows microcrystal native-SAD phasing from as few as about 1200 crystals. Finally, beyond microcrystals, our data analysis strategy may work equally well for microdiffraction data from larger crystals.

36 MATERIALS SCIENCE↗