Recycled Glass Fiber Reinforced Polymer Composites Incorporated in Mortar for Improved Mechanical Performance

Glass fiber reinforced polymer (GFRP) recycled from retired wind turbines was implemented in mortar as a volumetric replacement of sand during the two phases of this study. In Phase I, the mechanically refined GFRP particle sizes were sieved for four size groups to find the optimum size. In Phase II, the select GFRP size group was incorporated at three different volumetric replacements of sand to identify the optimum replacement content. The mixtures were tested for compressive strength, flexural strength, toughness, and the potential for alkali-silicate reaction. Incorporation of GFRP in mortar proves promising in improving flexural strength and toughness in fiber-like shapes and 1–3% volumetric fractions

Optical Excitation of a Nanoparticle Cu/p-NiO Photocathode Improves Reaction Selectivity for CO₂ Reduction in Aqueous Electrolytes

We report the light-induced modification of catalytic selectivity for photoelectrochemical CO₂ reduction in aqueous media using copper (Cu) nanoparticles dispersed onto p-type nickel oxide (p-NiO) photocathodes. Optical excitation of Cu nanoparticles generates hot electrons available for driving CO₂ reduction on the Cu surface, while charge separation is accomplished by hot-hole injection from the Cu nanoparticles into the underlying p-NiO support. Photoelectrochemical studies demonstrate that optical excitation of plasmonic Cu/p-NiO photocathodes imparts increased selectivity for CO₂ reduction over hydrogen evolution in aqueous electrolytes. Specifically, we observed that plasmon-driven CO₂ reduction increased the production of carbon monoxide and formate, while simultaneously reducing the evolution of hydrogen. Our results demonstrate an optical route toward steering the selectivity of artificial photosynthetic systems with plasmon-driven photocathodes for photoelectrochemical CO₂ reduction in aqueous media

ADVERTISING, STRUCTURAL CHANGE, AND U.S. NON-ALCOHOLIC BEVERAGE DEMAND

The dominant trend in U.S. non-alcoholic consumption over the past two decades has been a steady increase in soft-drink consumption, largely at the expense of milk and coffee and tea consumption. Our analysis suggests that the primary factors affecting this is that the price, advertising, and demographic elasticities estimated from the Rotterdam model are much smaller than the adjusted trend coefficients and the expenditure elasticities.Consumer/Household Economics, Demand and Price Analysis, Marketing,

Hot Hole Collection and Photoelectrochemical CO_2 Reduction with Plasmonic Au/p-GaN Photocathodes

Harvesting nonequilibrium hot carriers from plasmonic-metal nanostructures offers unique opportunities for driving photochemical reactions at the nanoscale. Despite numerous examples of hot electron-driven processes, the realization of plasmonic systems capable of harvesting hot holes from metal nanostructures has eluded the nascent field of plasmonic photocatalysis. Here, we fabricate gold/p-type gallium nitride (Au/p-GaN) Schottky junctions tailored for photoelectrochemical studies of plasmon-induced hot-hole capture and conversion. Despite the presence of an interfacial Schottky barrier to hot-hole injection of more than 1 eV across the Au/p-GaN heterojunction, plasmonic Au/p-GaN photocathodes exhibit photoelectrochemical properties consistent with the injection of hot holes from Au nanoparticles into p-GaN upon plasmon excitation. The photocurrent action spectrum of the plasmonic photocathodes faithfully follows the surface plasmon resonance absorption spectrum of the Au nanoparticles and open-circuit voltage studies demonstrate a sustained photovoltage during plasmon excitation. Comparison with Ohmic Au/p-NiO heterojunctions confirms that the vast majority of hot holes generated via interband transitions in Au are sufficiently hot to inject above the 1.1 eV interfacial Schottky barrier at the Au/p-GaN heterojunction. We further investigated plasmon-driven photoelectrochemical CO_2 reduction with the Au/p-GaN photocathodes and observed improved selectivity for CO production over H_2 evolution in aqueous electrolytes. Taken together, our results offer experimental validation of photoexcited hot holes more than 1 eV below the Au Fermi level and demonstrate a photoelectrochemical platform for harvesting hot carriers to drive solar-to-fuel energy conversion

Near-Unity Unselective Absorption in Sparse InP Nanowire Arrays

We experimentally demonstrate near-unity, unselective absorption, broadband, angle-insensitive, and polarization-independent absorption, in sparse InP nanowire arrays, embedded in flexible polymer sheets via geometric control of waveguide modes in two wire motifs: (i) arrays of tapered wires and (ii) arrays of nanowires with varying radii. Sparse arrays of these structures exhibit enhanced absorption due to strong coupling into the first order azimuthal waveguide modes of individual nanowires; wire radius thus controls the spectral region of the absorption enhancement. Whereas arrays of cylindrical wires with uniform radius exhibit narrowband absorption, arrays of tapered wires and arrays with multiple wire radii expand this spectral region and achieve broadband absorption enhancement. Herein, we present an economic, top-down lithographic/etch fabrication method that enables fabrication of multiple InP nanowire arrays from a single InP wafer with deliberate control of nanowire radius and taper. Using this method, we create sparse tapered and multiradii InP nanowire arrays and demonstrate optical absorption that is broadband (450–900 nm), angle-insensitive, and near-unity (>90%) in roughly 100 nm planar equivalence of InP. These highly absorbing sparse nanowire arrays represent a promising approach to flexible, high efficiency optoelectronic devices, such as photodetectors, solar cells, and photoelectrochemical devices

Ultrafast Studies of Hot-Hole Dynamics in Au/p-GaN Heterostructures

Harvesting non-equilibrium hot carriers from photo-excited metal nanoparticles has enabled plasmon-driven photochemical transformations and tunable photodetection with resonant nanoantennas. Despite numerous studies on the ultrafast dynamics of hot electrons, to date, the temporal evolution of hot holes in metal-semiconductor heterostructures remains unknown. An improved understanding of the carrier dynamics in hot-hole-driven systems is needed to help expand the scope of hot-carrier optoelectronics beyond hot-electron-based devices. Here, using ultrafast transient absorption spectroscopy, we show that plasmon-induced hot-hole injection from gold (Au) nanoparticles into the valence band of p-type gallium nitride (p-GaN) occurs within 200 fs, placing hot-hole transfer on a similar timescale as hot-electron transfer. We further observed that the removal of hot holes from below the Au Fermi level exerts a discernible influence on the thermalization of hot electrons above it, reducing the peak electronic temperature and decreasing the electron-phonon coupling time relative to Au samples without a pathway for hot-hole collection. First principles calculations corroborate these experimental observations, suggesting that hot-hole injection modifies the relaxation dynamics of hot electrons in Au nanoparticles through ultrafast modulation of the d-band electronic structure. Taken together, these ultrafast studies substantially advance our understanding of the temporal evolution of hot holes in metal-semiconductor heterostructures and suggest new strategies for manipulating and controlling the energy distributions of hot carriers on ultrafast timescales.Comment: 12 pages, 4 figure

Dynamic beam steering with all-dielectric electro-optic III-V multiple-quantum-well metasurfaces

Tunable metasurfaces enable dynamical control of the key constitutive properties of light at a subwavelength scale. To date, electrically tunable metasurfaces at near-infrared wavelengths have been realized using free carrier modulation, and switching of thermo-optical, liquid crystal and phase change media. However, the highest performance and lowest loss discrete optoelectronic modulators exploit the electro-optic effect in multiple-quantum-well heterostructures. Here, we report an all-dielectric active metasurface based on electro-optically tunable III–V multiple-quantum-wells patterned into subwavelength elements that each supports a hybrid Mie-guided mode resonance. The quantum-confined Stark effect actively modulates this volumetric hybrid resonance, and we observe a relative reflectance modulation of 270% and a phase shift from 0° to ~70°. Additionally, we demonstrate beam steering by applying an electrical bias to each element to actively change the metasurface period, an approach that can also realize tunable metalenses, active polarizers, and flat spatial light modulators

High Broadband Light Transmission for Solar Fuels Production Using Dielectric Optical Waveguides in TiO₂ Nanocone Arrays

We describe the fabrication and use of arrays of TiO₂ nanocones to yield high optical transmission into semiconductor photoelectrodes covered with high surface loadings of light-absorbing electrocatalysts. Covering over 50% of the surface of a light absorber with an array of high-refractive-index TiO₂ nanocones imparted antireflective behavior ( 85% transmission of broadband light to the underlying Si, even when thick metal contacts or opaque catalyst coatings were deposited on areas of the light-facing surface that were not directly beneath a nanocone. Three-dimensional full-field electromagnetic simulations for the 400 – 1100 nm spectral range showed that incident broadband illumination couples to multiple waveguide modes in the TiO₂ nanocones, reducing interactions of the light with the metal layer. A proof-of-concept experimental demonstration of light-driven water oxidation was performed using a p⁺n-Si photoanode decorated with an array of TiO₂ nanocones additionally having a Ni catalyst layer electrodeposited onto the areas of the p⁺n-Si surface left uncovered by the TiO₂ nanocones. This photoanode produced a light-limited photocurrent density of ~ 28 mA cm⁻² under 100 mW cm⁻² of simulated Air Mass 1.5 illumination, equivalent to the photocurrent density expected for a bare planar Si surface even though 54% of the front surface of the Si was covered by an ~ 70 nm thick Ni metal layer

Immunization expands B cells specific to HIV-1 V3 glycan in mice and macaques.

Broadly neutralizing monoclonal antibodies protect against infection with HIV-1 in animal models, suggesting that a vaccine that elicits these antibodies would be protective in humans. However, it has not yet been possible to induce adequate serological responses by vaccination. Here, to activate B cells that express precursors of broadly neutralizing antibodies within polyclonal repertoires, we developed an immunogen, RC1, that facilitates the recognition of the variable loop 3 (V3)-glycan patch on the envelope protein of HIV-1. RC1 conceals non-conserved immunodominant regions by the addition of glycans and/or multimerization on virus-like particles. Immunization of mice, rabbits and rhesus macaques with RC1 elicited serological responses that targeted the V3-glycan patch. Antibody cloning and cryo-electron microscopy structures of antibody-envelope complexes confirmed that immunization with RC1 expands clones of B cells that carry the anti-V3-glycan patch antibodies, which resemble precursors of human broadly neutralizing antibodies. Thus, RC1 may be a suitable priming immunogen for sequential vaccination strategies in the context of polyclonal repertoires