Related Publications

  • A path for lignin valorization via additive manufacturing of high-performance sustainable composites with enhanced 3D printability

    We report the manufacture of printable, sustainable polymer systems to address global challenges associated with high-volume utilization of lignin, an industrial waste from biomass feedstock. By analyzing a common three-dimensional printing process—fused-deposition modeling—and correlating the printing-process features to properties of materials such as acrylonitrile-butadiene-styrene (ABS) and nylon, we devised a first-of-its-kind, high-performance class of printable renewable composites containing 40 to 60 weight % (wt %) lignin. An ABS analog made by integrating lignin into nitrile-...
  • Mesoporous Carbon Materials: Synthesis and Modification

    Porous carbon materials are of interest in many applications because of their high surface area and physicochemical properties. Conventional syntheses can only produce randomly porous materials, with little control over the pore‐size distributions, let alone mesostructures. Recent breakthroughs in the preparation of other porous materials have resulted in the development of methods for the preparation of mesoporous carbon materials with extremely high surface areas and ordered mesostructures, with potential applications as catalysts, separation media, and advanced electronic materials in many...
  • Atomically dispersed manganese catalysts for oxygen reduction in proton-exchange membrane fuel cells

    Platinum group metal (PGM)-free catalysts that are also iron free are highly desirable for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells, as they avoid possible Fenton reactions. Here we report an efficient ORR catalyst that consists of atomically dispersed nitrogen-coordinated single Mn sites on partially graphitic carbon (Mn-N-C). Evidence for the embedding of the atomically dispersed MnN4 moieties within the carbon surface-exposed basal planes was established by X-ray absorption spectroscopy and their dispersion was confirmed by aberration-corrected electron...
  • A ternary memory cell using small Josephson junction arrays

    In this paper we present a ternary cryogenic memory cell paradigm that is based on an array of inductively coupled Josephson junctions. We show how reading, writing and resetting are implemented using single flux quantum current pulse inputs to the circuit and reading voltage pulse outputs from the circuit. We further show how both destructive readout and non-destructive readout can be implemented.
  • Continuum of quantum fluctuations in a three-dimensional S = 1 Heisenberg magnet

    Conventional crystalline magnets are characterized by symmetry breaking and normal modes of excitation called magnons, with quantized angular momentum ħ. Neutron scattering correspondingly features extra magnetic Bragg diffraction at low temperatures and dispersive inelastic scattering associated with single magnon creation and annihilation. Exceptions are anticipated in so-called quantum spin liquids, as exemplified by the one-dimensional spin-1/2 chain, which has no magnetic order and where magnons accordingly fractionalize into spinons with angular momentum ħ/2. This is spectacularly...
  • First Observation of P-odd γ Asymmetry in Polarized Neutron Capture on Hydrogen

    We report the first observation of the parity-violating gamma-ray asymmetry Anpγ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. Anpγ isolates the ΔI=1 , 3S1→3P1 component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory. We measured Anpγ=[−3.0±1.4(stat)±0.2(syst)]×10−8 , which implies a DDH weak πNN coupling of h1π=[2.6±...
  • Quantum interference and correlation control of frequency-bin qubits

    Frequency-bin quantum information encoding offers an intriguing synergy with classical optical networks, with the ability to support many qubits in a single fiber. Yet, coherent quantum frequency operations prove extremely challenging due to the difficulties in mixing frequencies arbitrarily and with low noise. In this paper, we address such challenges and implement distinct quantum gates in parallel on two entangled frequency-bin qubits in the same optical fiber. Our basic quantum operation controls the spectral overlap between adjacent spectral bins, allowing us to observe frequency-bin...
  • Methanogenic Archaea dominate mature heartwood habitats of Eastern Cottonwood (Populus deltoides)

    While recent reports demonstrate that the direct emission of methane from living tree trunks may be a significant terrestrial emission source, there has been debate whether tree emissions are due to transport from soils or produced in the wood environment itself. Reports of methanogens from wood of trees were prominent in the literature 40 years ago but have not been revisited with molecular ecology approaches. We examined communities associated with Populus deltoides using rRNA gene sequence analyses and how these vary with tree and wood properties. Our data indicate that wood...
  • Electrolyte Solvation Structure at Solid–Liquid Interface Probed by Nanogap Surface-Enhanced Raman Spectroscopy

    Understanding the fundamental factors that drive ion solvation structure and transport is key to design high-performance, stable battery electrolytes. Reversible ion solvation and desolvation are critical to the interfacial charge-transfer process across the solid–liquid interface as well as the resulting stability of the solid electrolyte interphase. Herein, we report the study of Li+ salt solvation structure in aprotic solution in the immediate vicinity (∼20 nm) of the solid electrode–liquid interface using surface-enhanced Raman spectroscopy (SERS) from a gold nanoparticle (Au NP)...
  • Multiagency Urban Search Experiment Detector and Algorithm Test Bed

    In order to provide benchmark data sets for radiation detector and algorithm development, a particle transport test bed has been created using experimental data as model input and validation. A detailed radiation measurement campaign at the Combined Arms Collective Training Facility in Fort Indiantown Gap, PA (FTIG), USA, provides sample background radiation levels for a variety of materials present at the site (including cinder block, gravel, asphalt, and soil) using long dwell high-purity germanium (HPGe) measurements. In addition, detailed light detection and ranging data and ground-truth...
  • Neutron decay correlations in the Nab experiment

    The Nab experiment will measure the correlation a between the momenta of the beta particle and antineutrino in neutron decay as well as the Fierz term b which distorts the beta spectrum.
  • Detection system for neutron β decay correlations in the UCNB and Nab experiments

    We describe a detection system designed for precise measurements of angular correlations in neutron β decay. The system is based on thick, large area, highly segmented silicon detectors developed in collaboration with Micron Semiconductor, Ltd. The prototype system meets specifications for β electron detection with energy thresholds below 10 keV, energy resolution of ∼3 keV FWHM, and rise time of ∼50 ns with 19 of the 127 detector pixels instrumented. Using ultracold neutrons at the Los Alamos Neutron Science Center, we have demonstrated the coincident detection of β particles and recoil...
  • Roll-to-Roll Processing of Silicon Carbide Nanoparticle-Deposited Carbon Fiber for Multifunctional Composites

    This work provides a proof of principle that a high volume, continuous throughput fiber coating process can be used to integrate semiconducting nanoparticles on carbon fiber surfaces to create multifunctional composites. By embedding silicon carbide nanoparticles in the fiber sizing, subsequent composite fabrication methods are used to create unidirectional fiber-reinforced composites with enhanced structural health monitoring (SHM) sensitivity and increased interlaminar strength. Additional investigations into the mechanical damping behavior of these functional composites reveal a...
  • Coordination and Control of Building HVAC Systems to Provide Frequency Regulation to the Electric Grid

    Buildings consume 73% of electricity produced in the United States and, currently, they are largely passive participants in the electric grid. However, the flexibility in building loads can be exploited to provide ancillary services to enhance the grid reliability. In this paper, we investigate two control strategies that allow Heating, Ventilation and Air-Conditioning (HVAC) systems in commercial and residential buildings to provide frequency regulation services to the grid while maintaining occupants comfort. The first optimal control strategy is based on model predictive control acting on...
  • The magic nature of 132Sn explored through the single-particle states of 133Sn

    Atomic nuclei have a shell structure1 in which nuclei with ‘magic numbers’ of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important2,3,4,5 for a...
  • Neutron-hole states in 131Sn and spin-orbit splitting in neutron-rich nuclei

    In atomic nuclei, the spin-orbit interaction originates from the coupling of the orbital motion of a nucleon with its intrinsic spin. Recent experimental and theoretical works have suggested a weakening of the spin-orbit interaction in neutron-rich nuclei far from stability. To study this phenomenon, we have investigated the spin-orbit energy splittings of single-hole and single-particle valence neutron orbits of 132Sn. The spectroscopic strength of single-hole states in 131Sn was determined from the measured differential cross sections of the tritons from the neutron-removing 132Sn(d, t)...
  • Impact of Partial Penetrations of Connected and Automated Vehicles on Fuel Consumption and Traffic Flow

    This article addresses the problem of analyzing the effects of partial penetrations of optimally coordinated connected and automated vehicles (CAVs) on fuel consumption and travel time under low, medium, and heavy traffic volumes. We develop a microscopic simulation framework to enhance our understanding of the interactions between human-driven vehicles and CAVs in a merging on-ramp scenario. We show that fuel consumption is adversely affected for medium and high traffic while benefits are realized for travel time under the same traffic conditions. We also show that higher penetrations of...
  • Decoding Oxyanion Aqueous Solvation Structure: A Potassium Nitrate Example at Saturation

    The ability to probe the structure of a salt solution at the atomic scale is fundamentally important for our understanding of many chemical reactions and their mechanisms. The capability of neutron diffraction to “see” hydrogen (or deuterium) and other light isotopes is exceptional for resolving the structural complexity around the dissolved solutes in aqueous electrolytes. We have made measurements using oxygen isotopes on aqueous nitrate to reveal a small hydrogen-bonded water coordination number (3.9 ± 1.2) around a nitrate oxyanion. This is compared to estimates made using the existing...
  • The structure around nitrate ions in concentrated aqueous solutions

    The first-order-difference method of neutron diffraction has been applied to a 7.8 molal aqueous solution of sodium nitrate in which isotopic substitutions were made on the nitrate ion. The intramolecular distance is found to be 1.23+or-0.02 AA. There are 1.3+or-0.2 water molecules coordinated axially to the nitrate ion with rND and RNO values of 2.05+or-0.02 and 2.65+or-0.10 AA respectively. A model for the longer-range structures is proposed.
  • Association mapping, transcriptomics, and transient expression identify candidate genes mediating plant–pathogen interactions in a tree

    Invasive microbes causing diseases such as sudden oak death negatively affect ecosystems and economies around the world. The deployment of resistant genotypes for combating introduced diseases typically relies on breeding programs that can take decades to complete. To demonstrate how this process can be accelerated, we employed a genome-wide association mapping of ca. 1,000 resequenced Populus trichocarpa trees individually challenged with Sphaerulina musiva, an invasive fungal pathogen. Among significant associations, three loci associated with resistance were identified and predicted to...
  • Building Structures Atom by Atom via Electron Beam Manipulation

    Building materials from the atom up is the pinnacle of materials fabrication. Until recently the only platform that offered single‐atom manipulation was scanning tunneling microscopy. Here controlled manipulation and assembly of a few atom structures are demonstrated by bringing together single atoms using a scanning transmission electron microscope. An atomically focused electron beam is used to introduce Si substitutional defects and defect clusters in graphene with spatial control of a few nanometers and enable controlled motion of Si atoms. The Si substitutional defects are then further...
  • Chemical nature of ferroelastic twin domains in CH3NH3PbI3 perovskite

    The extraordinary optoelectronic performance of hybrid organic–inorganic perovskites has resulted in extensive efforts to unravel their properties. Recently, observations of ferroic twin domains in methylammonium lead triiodide drew significant attention as a possible explanation for the current–voltage hysteretic behaviour in these materials. However, the properties of the twin domains, their local chemistry and the chemical impact on optoelectronic performance remain unclear. Here, using multimodal chemical and functional imaging methods, we unveil the mechanical origin of the twin domain...
  • Grazing-Angle Neutron Diffraction Study of the Water Distribution in Membrane Hemifusion: From the Lamellar to Rhombohedral Phase

    The water distribution between lipid bilayers is important in understanding the role of the hydration force at different steps of the membrane fusion pathway. In this study, we used grazing-angle neutron diffraction to map out the water distribution in lipid bilayers transiting from a lamellar structure to the hemifusion “stalk” structure in a rhombohedral phase. Under osmotic pressure exerted by different levels of relative humidity, the lipid membrane sample was maintained in equilibrium at different lattices suitable for neutron diffraction. The D2O used to hydrate the lipid membrane...
  • Application of Polynomial Chaos Expansion in Inverse Transport Problems with Neutron Multiplication Measurements and Multiple Unknowns

    The polynomial chaos expansion technique is used to build surrogate models of the dependences of gamma-ray fluxes and neutron multiplication to unknown physical parameters in radiological source/shield systems. These surrogate models are used with the DiffeRential Evolution Adaptive Metropolis (DREAM), a method to solve and quantify uncertainty in inverse transport problems. Measured data in the inverse problems includes both passive gamma rays and neutron multiplication. The polynomial chaos expansion approach is shown to increase the speed...
  • Organic agents offer innovation

    Capturing CO2 directly from the air could lead to negative emissions, but more efficient technologies are still required. Now, researchers use a multi-stage cycle based on amino acids and organic salts to capture CO2 from air, which can be released with concentrated solar power.