8 research outputs found
ELECTROPHORETIC DISPLAYS WITH TUNABLE, ANGLE-INDEPENDENT COLOR
Electrophoretic displays (EPDs), which exploit the surface charge of microparticles to control their deposition, have become widely available in consumer electronics, such as e-readers and smartwatches. However, a full-color EPD has yet to be demonstrated and commercialized. Here, we demonstrate colloidal assemblies of engineered quasi-amorphous photonic materials, using pigmentary α-Fe2O3/SiO2 core/shell nanoparticles, exhibiting non- iridescent tunable colors which can be tuned electrophoretically. The observed colors result from combination of colloidal particle arrangements, giving rise to structural color, along with the inherent pigmentary color of the α-Fe2O3/SiO2 nanoparticles. Colloidal particle assemblies of α-Fe2O3/SiO2 core/shell nanoparticles, and therefore the resulting colors, can be manipulated by shell thickness, particle concentration and external electrical stimuli. Dynamic tunability of α-Fe2O3/SiO2 nanomaterials in the visible wavelengths is demonstrated using reversible electrophoretic deposition with a noticeable difference between transmitted and reflected colors. The distinct contrast generated can be exploited for tunable display applications.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-704082
In-situ USAXS/SAXS Investigation of Tunable Structural Color in Amorphous Photonic Crystals during Electrophoretic Deposition
Amorphous photonic crystals (APCs) formed via electrophoretic deposition (EPD) exhibit non-iridescent, angle-independent, structural colors believed to arise from changes in the particle-particle interactions and inter-particle spacing, representing a potential new paradigm for display technologies. However, inter-particle dynamics on nanometer length scales that govern (and enable control over) the displayed color, crystallinity, and other characteristics of the photonic structures, are not well understood. Unfortunately, typical lab-based characterization techniques such as SEM, TEM, and Computed Tomography (CT) are generally performed ex-situ once the sample deposit has been dried. In this work, in-situ USAXS/SAXS/WAXS studies of three-dimensional colloidal particle arrays (of varying particle size and concentration) were performed in order to identify their structural response to applied external electric fields. This data was compared to simultaneously acquired UV-Vis spectra to tie the overall electrically induced structure of the APCs directly to the observed changes in visible color. The structural evolution of the APCs provides new information regarding the correlation between nano-scale particle-particle interactions and the corresponding optical response. To our knowledge, there has been no other prior studies examining the structure of APCs during the application of an electric field. This novel, in-situ USAXS study has helped to gain a better fundamental understanding of how the properties of APCs can be controlled for the advancement of optical displays.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-725437-DRAF
Multi-ancestry genome-wide association meta-analysis of Parkinson?s disease
Although over 90 independent risk variants have been identified for Parkinson’s disease using genome-wide association studies, most studies have been performed in just one population at a time. Here we performed a large-scale multi-ancestry meta-analysis of Parkinson’s disease with 49,049 cases, 18,785 proxy cases and 2,458,063 controls including individuals of European, East Asian, Latin American and African ancestry. In a meta-analysis, we identified 78 independent genome-wide significant loci, including 12 potentially novel loci (MTF2, PIK3CA, ADD1, SYBU, IRS2, USP8, PIGL, FASN, MYLK2, USP25, EP300 and PPP6R2) and fine-mapped 6 putative causal variants at 6 known PD loci. By combining our results with publicly available eQTL data, we identified 25 putative risk genes in these novel loci whose expression is associated with PD risk. This work lays the groundwork for future efforts aimed at identifying PD loci in non-European populations
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Design of Materials for Energy Conversion, Storage and CO2 Capture
I will discuss the design of functional materials for energy conversion, storage, and CO2 capture projects. Chapter 1 introduces two different methods, 3D printing and freeze casting, to provide a desired structure to a material. Two different approaches of 3D printing will be explored: stereolithography and direct ink writing. We will also look at freeze casting as a method to introduce a templated structure, based on the formation of ice crystals, to a material. We will then discuss common drying methods coupled with these techniques to preserver the desired structure.Chapter 2 focuses on the development of a conductive 3D printable living ink containing Shewanella Oneidensis MR-1, for use as an organic matter oxidizing anode in a microbial fuel cell to generate bioelectricity. The capability of printing living and functional 3D bacterial structures could open new possibilities in design and fabrication of microbial devices as well as fundamental research on the interactions between different bacterial strains, electrode materials, and surrounding environments.
In the second project shown in Chapter 3, I extend the synthetic capability to the high resolution direct-ink-write printing of resorcinol-formaldehyde based materials. Highly conductive carbon scaffolds with well-defined porous structures can be derived from these 3D printed polymer materials via a combination of freeze drying and carbonization processes. 3D printed carbon structures can be implemented as a host material for lithium metal for use as an anode in solid-state batteries to improve their cyclability, safety and energy density.
I will present some preliminary results on using cellulose-derived carbon materials for CO2 capture in Chapter 4. The goal is to improve the understanding of the inherent structure and composition of the cellulose-carbon materials interplay with their CO2 capture ability. The cellulose material will be used without chemical modifications to the starting cellulose material. CO2 capture will be achieved through the inherit surface functional groups and structure which can be introduced via freeze casting.
In Chapter 5 I will present an intensive literature review to show the current state of reactive capture technologies. Carbon dioxide (CO2) capture and CO2 conversion have traditionally been treated as distinct application areas with non-overlapping research programs. However, the integration of capture and conversion processes presents an opportunity to eliminate energy penalties, costs, and logistical hurdles inherent in the separation of CO2 from mixed gas streams, regeneration of the capture material/solvent, compression of CO2, and transport to a conversion facility. By integrating the two processes, which we term “reactive capture”, CO2 can be separated from a mixed gas stream and converted to valuable products using process steps that eliminate sorbent regeneration, CO2 compression, and transportation
Electro-Optical Device with Tunable Transparency Using Colloidal Core/Shell Nanoparticles
Suspended particle
devices (SPDs) adapted for controlling the transmission of electromagnetic
radiation have become an area of considerable focus for smart window
technology due to their desirable properties, such as instant and
precise light control and cost-effectiveness. Here, we demonstrate
a SPD with tunable transparency in the visible regime using colloidal
assemblies of nanoparticles. The observed transparency using ZnS/SiO<sub>2</sub> core/shell colloidal nanoparticles is dynamically tunable
in response to an external electric field with increased transparency
when applied voltage increases. The observed transparency change is
attributed to structural ordering of nanoparticle assemblies and thereby
modifies the photonic band structures, as confirmed by the finite-difference
time-domain simulations of Maxwell’s equations. The transparency
of the device can also be manipulated by changing the particle size
and the device thickness. In addition to transparency, structural
colorations and their dynamic tunability are demonstrated using α-Fe<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> core/shell nanomaterials, resulting
from the combination of inherent optical properties of α-Fe<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> nanomaterials and coloration
due to their tunable structural particle assemblies in response to
electric stimuli
Electro-Optical Device with Tunable Transparency Using Colloidal Core/Shell Nanoparticles
Suspended particle
devices (SPDs) adapted for controlling the transmission of electromagnetic
radiation have become an area of considerable focus for smart window
technology due to their desirable properties, such as instant and
precise light control and cost-effectiveness. Here, we demonstrate
a SPD with tunable transparency in the visible regime using colloidal
assemblies of nanoparticles. The observed transparency using ZnS/SiO<sub>2</sub> core/shell colloidal nanoparticles is dynamically tunable
in response to an external electric field with increased transparency
when applied voltage increases. The observed transparency change is
attributed to structural ordering of nanoparticle assemblies and thereby
modifies the photonic band structures, as confirmed by the finite-difference
time-domain simulations of Maxwell’s equations. The transparency
of the device can also be manipulated by changing the particle size
and the device thickness. In addition to transparency, structural
colorations and their dynamic tunability are demonstrated using α-Fe<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> core/shell nanomaterials, resulting
from the combination of inherent optical properties of α-Fe<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> nanomaterials and coloration
due to their tunable structural particle assemblies in response to
electric stimuli
Electro-Optical Device with Tunable Transparency Using Colloidal Core/Shell Nanoparticles
Suspended particle
devices (SPDs) adapted for controlling the transmission of electromagnetic
radiation have become an area of considerable focus for smart window
technology due to their desirable properties, such as instant and
precise light control and cost-effectiveness. Here, we demonstrate
a SPD with tunable transparency in the visible regime using colloidal
assemblies of nanoparticles. The observed transparency using ZnS/SiO<sub>2</sub> core/shell colloidal nanoparticles is dynamically tunable
in response to an external electric field with increased transparency
when applied voltage increases. The observed transparency change is
attributed to structural ordering of nanoparticle assemblies and thereby
modifies the photonic band structures, as confirmed by the finite-difference
time-domain simulations of Maxwell’s equations. The transparency
of the device can also be manipulated by changing the particle size
and the device thickness. In addition to transparency, structural
colorations and their dynamic tunability are demonstrated using α-Fe<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> core/shell nanomaterials, resulting
from the combination of inherent optical properties of α-Fe<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> nanomaterials and coloration
due to their tunable structural particle assemblies in response to
electric stimuli
Ultralight Conductive Silver Nanowire Aerogels
Low-density
metal foams have many potential applications in electronics,
energy storage, catalytic supports, fuel cells, sensors, and medical
devices. Here, we report a new method for fabricating ultralight,
conductive silver aerogel monoliths with predictable densities using
silver nanowires. Silver nanowire building blocks were prepared by
polyol synthesis and purified by selective precipitation. Silver aerogels
were produced by freeze-casting nanowire aqueous suspensions followed
by thermal sintering to weld the nanowire junctions. As-prepared silver
aerogels have unique anisotropic microporous structures, with density
precisely controlled by the nanowire concentration, down to 4.8 mg/cm<sup>3</sup> and an electrical conductivity up to 51 000 S/m. Mechanical
studies show that silver nanowire aerogels exhibit “elastic
stiffening” behavior with a Young’s modulus up to 16 800
Pa