34 research outputs found
Density of Common Complex Ocular Traits in the Aging Eye: Analysis of Secondary Traits in Genome-Wide Association Studies
Genetic association studies are identifying genetic risks for common complex ocular traits such as age-related macular degeneration (AMD). The subjects used for discovery of these loci have been largely from clinic-based, case-control studies. Typically, only the primary phenotype (e.g., AMD) being studied is systematically documented and other complex traits (e.g., affecting the eye) are largely ignored. The purpose of this study was to characterize these other or secondary complex ocular traits present in the cases and controls of clinic-based studies being used for genetic study of AMD. The records of 100 consecutive new patients (of any diagnosis) age 60 or older for which all traits affecting the eye had been recorded systematically were reviewed. The average patient had 3.5 distinct diagnoses. A subset of 10 complex traits was selected for further study because they were common and could be reliably diagnosed. The density of these 10 complex ocular traits increased by 0.017 log-traits/year (P = 0.03), ranging from a predicted 2.74 at age 60 to 4.45 at age 90. Trait-trait association was observed only between AMD and primary vitreomacular traction (P = 0.0009). Only 1% of subjects age 60 or older had no common complex traits affecting the eye. Extrapolations suggested that a study of 2000 similar subjects would have sufficient power to detect genetic association with an odds ratio of 2.0 or less for 4 of these 10 traits. In conclusion, the high prevalence of complex traits affecting the aging eye and the inherent biases in referral patterns leads to the potential for confounding by undocumented secondary traits within case-control studies. In addition to the primary trait, other common ocular phenotypes should be systematically documented in genetic association studies so that adjustments for potential trait-trait associations and other bias can be made and genetic risk variants identified in secondary analyses
Influence of Crystalline and Shape Anisotropy on Electrochromic Modulation in Doped Semiconductor Nanocrystals
Localized surface plasmon resonance (LSPR)
modulation appearing in the near-infrared range in doped semiconductor
nanocrystals enriches electrochromic performance. Although crystalline and
shape anisotropies influence LSPR spectra, study of their impact on
electrochromic modulation are lacking. Here, we study how crystalline
anisotropy in hexagonal cesium-doped tungsten oxide nanorods and nanoplatelets
affects essential metrics of electrochromic modulation—coloration efficiency
(CE) and volumetric capacity—using different sizes of electrolyte cations
(tetrabutylammonium, sodium, and lithium) as structurally sensitive
electrochemical probes. Nanorod films show higher CE than nanoplatelets in all
of electrolytes owing to low effective mass along the crystalline c-axis. When
using sodium cations, which diffuse through one-dimensional hexagonal tunnels,
electrochemical capacity is significantly greater for platelets than for
nanorods. This difference is explained by the hexagonal tunnel sites being more
accessible in platelets than in nanorods. Our work sheds light on the role of
shape and crystalline anisotropy on charge capacity and CE both of which
contribute to overall modulation. </p
Spectroelectrochemical Signatures of Capacitive Charging and Ion Insertion in Doped Anatase Titania Nanocrystals
Solution-processed
films of colloidal aliovalent niobium-doped
anatase TiO<sub>2</sub> nanocrystals exhibit modulation of optical
transmittance in two spectral regionsî—¸near-infrared (NIR) and
visible lightî—¸as they undergo progressive and reversible charging
in an electrochemical cell. The Nb-TiO<sub>2</sub> nanocrystal film
supports a localized surface plasmon resonance in the NIR, which can
be dynamically modulated via capacitive charging. When the nanocrystals
are charged by insertion of lithium ions, inducing a well-known structural
phase transition of the anatase lattice, strong modulation of visible
transmittance is observed. Based on X-ray absorption near-edge spectroscopy,
the conduction electrons localize only upon lithium ion insertion,
thus rationalizing the two modes of optical switching observed in
a single material. These multimodal electrochromic properties show
promise for application in dynamic optical filters or smart windows
Resolving the Growth of 3D Colloidal Nanoparticle Superlattices by Real-Time Small-Angle X‑ray Scattering
The kinetics and intricate interactions governing the
growth of
3D single nanoparticle (NP) superlattices (SLs, SNSLs) and binary
NP SLs (BNSLs) in solution are understood by combining controlled
solvent evaporation and <i>in situ</i>, real-time small-angle
X-ray scattering (SAXS). For the iron oxide (magnetite) NP SLs studied
here, the larger the NP, the farther apart are the NPs when the SNSLs
begin to precipitate and the closer they are after ordering. This
is explained by a model of NP assembly using van der Waals interactions
between magnetite cores in hydrocarbons with a ∼21 zJ Hamaker
constant. When forming BNSLs of two different sized NPs, the NPs that
are in excess of that needed to achieve the final BNSL stoichiometry
are expelled during the BNSL formation, and these expelled NPs can
form SNSLs. The long-range ordering of these SNSLs and the BNSLs can
occur faster than the NP expulsion
Resolving the Growth of 3D Colloidal Nanoparticle Superlattices by Real-Time Small-Angle X‑ray Scattering
The kinetics and intricate interactions governing the
growth of
3D single nanoparticle (NP) superlattices (SLs, SNSLs) and binary
NP SLs (BNSLs) in solution are understood by combining controlled
solvent evaporation and <i>in situ</i>, real-time small-angle
X-ray scattering (SAXS). For the iron oxide (magnetite) NP SLs studied
here, the larger the NP, the farther apart are the NPs when the SNSLs
begin to precipitate and the closer they are after ordering. This
is explained by a model of NP assembly using van der Waals interactions
between magnetite cores in hydrocarbons with a ∼21 zJ Hamaker
constant. When forming BNSLs of two different sized NPs, the NPs that
are in excess of that needed to achieve the final BNSL stoichiometry
are expelled during the BNSL formation, and these expelled NPs can
form SNSLs. The long-range ordering of these SNSLs and the BNSLs can
occur faster than the NP expulsion
Resolving the Growth of 3D Colloidal Nanoparticle Superlattices by Real-Time Small-Angle X‑ray Scattering
The kinetics and intricate interactions governing the
growth of
3D single nanoparticle (NP) superlattices (SLs, SNSLs) and binary
NP SLs (BNSLs) in solution are understood by combining controlled
solvent evaporation and <i>in situ</i>, real-time small-angle
X-ray scattering (SAXS). For the iron oxide (magnetite) NP SLs studied
here, the larger the NP, the farther apart are the NPs when the SNSLs
begin to precipitate and the closer they are after ordering. This
is explained by a model of NP assembly using van der Waals interactions
between magnetite cores in hydrocarbons with a ∼21 zJ Hamaker
constant. When forming BNSLs of two different sized NPs, the NPs that
are in excess of that needed to achieve the final BNSL stoichiometry
are expelled during the BNSL formation, and these expelled NPs can
form SNSLs. The long-range ordering of these SNSLs and the BNSLs can
occur faster than the NP expulsion
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Ferroelastic Hysteresis in Thin Films of Methylammonium Lead Iodide
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Ferroelastic Hysteresis in Thin Films of Methylammonium Lead Iodide
Electrochemically Induced Transformations of Vanadium Dioxide Nanocrystals
Vanadium dioxide (VO<sub>2</sub>)
undergoes significant optical, electronic, and structural changes
as it transforms between the low-temperature monoclinic and high-temperature
rutile phases. Recently, alternative stimuli have been utilized to
trigger insulator-to-metal transformations in VO<sub>2</sub>, including
electrochemical gating. Here, we prepare and electrochemically reduce
mesoporous films of VO<sub>2</sub> nanocrystals, prepared from colloidally
synthesized V<sub>2</sub>O<sub>3</sub> nanocrystals that have been
oxidatively annealed, in a three-electrode electrochemical cell. We
observe a reversible transition between infrared transparent insulating
phases and a darkened metallic phase by in situ visible–near-infrared
spectroelectrochemistry and correlate these observations with structural
and electronic changes monitored by X-ray absorption spectroscopy,
X-ray diffraction, Raman spectroscopy, and conductivity measurements.
An unexpected reversible transition from conductive, reduced monoclinic
VO<sub>2</sub> to an infrared-transparent insulating phase upon progressive
electrochemical reduction is observed. This insulator–metal–insulator
transition has not been reported in previous studies of electrochemically
gated epitaxial VO<sub>2</sub> films and is attributed to improved
oxygen vacancy formation kinetics and diffusion due to the mesoporous
nanocrystal film structure