Strong Influence of Coadsorbate Interaction on CO Desorption Dynamics on Ru(0001) Probed by Ultrafast X-Ray Spectroscopy and Ab Initio Simulations
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Xin, H.↗
SEARCH · Engineering Papers
Results for “strong interaction”
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Hubbard physics in the PAW GW approximation
It is demonstrated that the signatures of the Hubbard Model in the strongly interacting regime can be simulated by modifying the screening in the limit of zero wavevector in Projector-Augmented Wave GW calculations for systems without significant nesting. This modification, when applied to the Mott insulator CuO, results in the opening of the Mott gap by the splitting of states at the Fermi level into upper and lower Hubbard bands, and exhibits a giant transfer of spectral weight upon electron doping. The method is also employed to clearly illustrate that the M{sub 1} and M{sub 2} forms of vanadium dioxide are fundamentally different types of insulator. Standard GW calculations are sufficient to open a gap in M{sub 1} VO{sub 2}, which arise from the Peierls pairing filling the valence band, creating homopolar bonds. The valence band wavefunctions are stabilized with respect to the conduction band, reducing polarizability and pushing the conduction band eigenvalues to higher energy. The M{sub 2} structure, however, opens a gap from strong on-site interactions; it is a Mott insulator.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Measurement of low-$p_T$ $D^+$ meson production cross-section at CDF II
In this paper I report on a measurement of the low- p T D + -meson production cross-section in proton-antiproton collisions at 1.96 TeV center-of-mass energy, using the full data set collected by the CDF experiment at the Tevatron collider during Run II. The measurement is performed in a yet unexplored low transverse momentum range, down to 1.5 GeV/ c . The actual QCD theory cannot predict the behavior of the strong interactions in the low transferred-four-momentum region because in these kinematic conditions the strong coupling constant is of the order of the unity. Thus, a perturbative expansion is not useful. At present, several phenomenological models have been proposed, but they are able to describe only a few aspects of the observed physical quantities and not the full complexity. Experimental results in these conditions are then crucial to test new QCD models. The measurement of the differential cross section at low p T plays an important role in this context allowing refinement of current knowledge. While these results lie within the band of theoretical uncertainty, differences in shape suggest that theoretical predictions can benefit from further refinement taking account of them.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Bilayer Wigner crystals in a transition metal dichalcogenide heterostructure
One of the first theoretically predicted manifestations of strong interactions in many-electron systems was the Wigner crystal, in which electrons crystallize into a regular lattice. The crystal can melt via either thermal or quantum fluctuations. Quantum melting of the Wigner crystal is predicted to produce exotic intermediate phases and quantum magnetism because of the intricate interplay of Coulomb interactions and kinetic energy. However, studying two-dimensional Wigner crystals in the quantum regime has often required a strong magnetic field or a moiré superlattice potential, thus limiting access to the full phase diagram of the interacting electron liquid. Here we report the observation of bilayer Wigner crystals without magnetic fields or moiré potentials in an atomically thin transition metal dichalcogenide heterostructure, which consists of two MoSe 2 monolayers separated by hexagonal boron nitride. We observe optical signatures of robust correlated insulating states at symmetric (1:1) and asymmetric (3:1, 4:1 and 7:1) electron doping of the two MoSe 2 layers at cryogenic temperatures. Here, we attribute these features to bilayer Wigner crystals composed of two interlocked commensurate triangular electron lattices, stabilized by inter-layer interaction. The Wigner crystal phases are remarkably stable, and undergo quantum and thermal melting transitions at electron densities of up to 6 × 10 12 per square centimetre and at temperatures of up to about 40 kelvin. Our results demonstrate that an atomically thin heterostructure is a highly tunable platform for realizing many-body electronic states and probing their liquid–solid and magnetic quantum phase transitions.
36 MATERIALS SCIENCE↗
Floquet Engineering of Interactions and Entanglement in Periodically Driven Rydberg Chains
Neutral atom arrays driven into Rydberg states constitute a promising approach for realizing programmable quantum systems. Enabled by strong interactions associated with Rydberg blockade, they allow for simulation of complex spin models and quantum dynamics. We introduce a new Floquet engineering technique for systems in the blockade regime that provides control over novel forms of interactions and entanglement dynamics in such systems. Our approach is based on time-dependent control of Rydberg laser detuning and leverages perturbations around periodic many-body trajectories as resources for operator spreading. These time-evolved operators are utilized as a basis for engineering interactions in the effective Hamiltonian describing the stroboscopic evolution. As an example, we show how our method can be used to engineer strong spin exchange, consistent with the blockade, in a one-dimensional chain, enabling the exploration of gapless Luttinger liquid phases. In addition, we demonstrate that combining gapless excitations with Rydberg blockade can lead to dynamic generation of large-scale multipartite entanglement. Experimental feasibility and possible generalizations are discussed.
Floquet systems↗
Design and Beam Test Results for the sPHENIX Electromagnetic and Hadronic Calorimeter Prototypes
The super Pioneering High Energy Nuclear Interaction eXperiment (sPHENIX) at the Relativistic Heavy Ion Collider (RHIC) will perform high precision measurements of jets and heavy flavor observables for a wide selection of nuclear collision systems, elucidating the microscopic nature of strongly interacting matter ranging from nucleons to the strongly coupled quark-gluon plasma. A prototype of the sPHENIX calorimeter system was tested at the Fermilab Test Beam Facility as experiment T-1044 in the spring of 2016. The electromagnetic calorimeter (EMCal) prototype is composed of scintillating fibers embedded in a mixture of tungsten powder and epoxy. The hadronic calorimeter (HCal) prototype is composed of tilted steel plates alternating with plastic scintillator. Results of the test beam reveal the energy resolution for electrons in the EMCal is $2.8\%\oplus~15.5\%/\sqrt{E}$ and the energy resolution for hadrons in the combined EMCal plus HCal system is $13.5\%\oplus 64.9\%/\sqrt{E}$. These results demonstrate that the performance of the proposed calorimeter system satisfies the sPHENIX specifications.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Hypersonic viscous interaction on sharp and blunt inclined plates.
Mach 42 test measuring surface pressures, surface heat transfer rates and shock wave shapes in strong interaction regime for sharp and blunt plates
Kemp, J. H., Jr.↗
Hypersonic viscous interaction on sharp and blunt inclined plates.
Mach 42 test measuring surface pressures, surface heat transfer rates and shock wave shapes in strong interaction regime for sharp and blunt plates
Kemp, J. H., Jr.↗
A simulation language approach to structural interaction problems
Advantages and disadvantages of using simulation languages in solving structural problems are given. Structural and solid mechanics problems which have strong interactions with other disciplines are emphasized. An aeroservoelastic illustration is described with significant interactions between the dynamics of a flexible flight vehicle structure, the aerodynamics to which it is subjected, the dynamic flight equations, and the vehicle's servo-control system.
Cutchins, M. A.↗
MEIC Detector and Interaction Region at JLab
The Electron-Ion Collider (EIC) is envisioned as the next-generation US facility for exploring the strong interaction. The Medium-energy EIC (MEIC) is the first stage of the EIC at Jefferson Lab (JLab). It's aimed at mapping the spin and spatial structure of the quark and gluon sea in the nucleon, understanding the emergence of hadronic matter from color charge, and probing the gluon fields in nuclei. A full-acceptance detector is designed to measure the complete final state. Its interaction region allows spectators tagged with high resolution to catch all nuclear and partonic target fragments. The combination of a high luminosity, polarized lepton and ion beams, and detectors fully integrated with the accelerator will allow MEIC to be a unique opportunity to make breakthroughs in the study of nucleon structure and QCD dynamics.
43 PARTICLE ACCELERATORS↗
Reconfigurable training and reservoir computing in an artificial spin-vortex ice via spin-wave fingerprinting
Strongly interacting artificial spin systems are moving beyond mimicking naturally occurring materials to emerge as versatile functional platforms, from reconfigurable magnonics to neuromorphic computing. Typically, artificial spin systems comprise nanomagnets with a single magnetization texture: collinear macrospins or chiral vortices. Here, by tuning nanoarray dimensions we have achieved macrospin–vortex bistability and demonstrated a four-state metamaterial spin system, the ‘artificial spin-vortex ice’ (ASVI). ASVI can host Ising-like macrospins with strong ice-like vertex interactions and weakly coupled vortices with low stray dipolar field. Vortices and macrospins exhibit starkly differing spin-wave spectra with analogue mode amplitude control and mode frequency shifts of Δf = 3.8 GHz. The enhanced bitextural microstate space gives rise to emergent physical memory phenomena, with ratchet-like vortex injection and history-dependent non-linear fading memory when driven through global magnetic field cycles. We employed spin-wave microstate fingerprinting for rapid, scalable readout of vortex and macrospin populations, and leveraged this for spin-wave reservoir computation. ASVI performs non-linear mapping transformations of diverse input and target signals in addition to chaotic time-series forecasting.
97 MATHEMATICS AND COMPUTING↗
A Pseudo‐Surfactant Chemical Permeation Enhancer to Treat Otitis Media via Sustained Transtympanic Delivery of Antibiotics
Abstract Chemical permeation enhancers (CPEs) represent a prevalent and safe strategy to enable noninvasive drug delivery across skin‐like biological barriers such as the tympanic membrane (TM). While most existing CPEs interact strongly with the lipid bilayers in the stratum corneum to create defects as diffusion paths, their interactions with the delivery system, such as polymers forming a hydrogel, can compromise gelation, formulation stability, and drug diffusion. To overcome this challenge, differing interactions between CPEs and the hydrogel system are explored, especially those with sodium dodecyl sulfate (SDS), an ionic surfactant and a common CPE, and those with methyl laurate (ML), a nonionic counterpart with a similar length alkyl chain. Notably, the use of ML effectively decouples permeation enhancement from gelation, enabling sustained delivery across TMs to treat acute otitis media (AOM), which is not possible with the use of SDS. Ciprofloxacin and ML are shown to form a pseudo‐surfactant that significantly boosts transtympanic permeation. The middle ear ciprofloxacin concentration is increased by 70‐fold in vivo in a chinchilla AOM model, yielding superior efficacy and biocompatibility than the previous highest‐performing formulation. Beyond improved efficacy and biocompatibility, this single‐CPE formulation significantly accelerates its progression toward clinical deployment.
Engineering↗
Design of gem -Difluoro- bis -Tetrahydrofuran as P2 Ligand for HIV-1 Protease Inhibitors to Improve Brain Penetration: Synthesis, X-ray Studies, and Biological Evaluation
The structure–based design, synthesis, biological evaluation, and X–ray structural studies of fluorine–containing HIV–1 protease inhibitors are described. The synthesis of both enantiomers of the gem–difluoro–bis–THF ligands was carried out in a stereoselective manner using a Reformatskii–Claisen reaction as the key step. Optically active ligands were converted into protease inhibitors. Two of these inhibitors, (3R,3aS,6aS)–4,4–difluorohexahydrofuro[2,3–b]furan–3–yl(2S,3R)–3–hydroxy–4–((N–isobutyl–4–methoxyphenyl)sulfonamido)–1–phenylbutan–2–yl) carbamate (3) and (3R,3aS,6aS)–4,4–difluorohexahydrofuro[2,3–b]furan–3–yl(2S,3R)–3–hydroxy–4–((N–isobutyl–4–aminophenyl)sulfonamido)phenylbutan–2–yl) carbamate (4), exhibited HIV–1 protease inhibitory K i values in the picomolar range. Both 3 and 4 showed very potent antiviral activity, with respective EC 50 values of 0.8 and 3.1 nM against the laboratory strain HIV–1 LAI . The two inhibitors exhibited better lipophilicity profiles than darunavir, and also showed much improved blood–brain barrier permeability in an in vitro model. A high–resolution X–ray structure of inhibitor 4 in complex with HIV–1 protease was determined, revealing that the fluorinated ligand makes extensive interactions with the S2 subsite of HIV–1 protease, including hydrogen bonding interactions with the protease backbone atoms. Moreover, both fluorine atoms on the bis–THF ligand formed strong interactions with the flap Gly 48 carbonyl oxygen atom.
59 BASIC BIOLOGICAL SCIENCES↗
Heat capacity and thermodynamic functions of partially dehydrated cation-exchanged (Na + , Cs + , Cd 2+ , Li + , and NH 4 + ) $\mathrm{RHO}$ zeolites
Synthetic zeolites have a myriad of applications in industry due to their porous frameworks, potential to exhibit flexibility, and specific interactions with guest molecules. One topology of zeolites, RHO, is known to be flexible and have strong interactions with both H 2 O and CO 2 . Here we have performed heat capacity measurements on three partially dehydrated zeolite RHO samples containing extra-framework cations Na + and Cs + , Cd 2+ and Cs + , and Li + and NH 4 + to understand the energetics of these materials. Based on fits of the heat capacity data, we report smooth thermodynamic functions of C p,m , Δ T 0 S m °, Δ T 0 H m °, and Φ m ° for these samples. The standard S m ° at 298.15 K are 76.3 ± 0.8, 72.1 ± 0.8, and 68.8 ± 0.7 J∙K -1 ∙mol -1 for the Na,Cs RHO, Cd,Cs RHO, and Li,NH 4 RHO samples, respectively, and the standard H m ° at 298.15 K are 12.1 ± 0.1, 11.4 ± 0.1, and 11.4 ± 0.1 kJ∙mol -1 . Our measurements also show a transition in the heat capacity of Na,Cs RHO, the sample with the highest water content, between 180 and 300 K that is not clearly observed in the other two samples. We attribute this transition to labile water and cations in the framework. This movement could also be coupled with a temperature-induced lattice expansion. Future work will include heat capacity measurements on fully dehydrated and fully hydrated zeolite RHO in order to separate these two possible phenomena.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Tunneling between two systems of interacting chiral fermions
Here, we develop a theory of tunneling between two systems of spinless chiral fermions. This setup can be realized at the edge of a quantum Hall bilayer structure. We find that the differential conductance of such a device in the absence of interactions has an infinitely sharp peak as a function of applied voltage. Interaction between fermions results in broadening of the conductance peak. We focus on the regime of strong interactions, in which the shape of the peak manifests well defined features associated with the elementary excitations of the system.
36 MATERIALS SCIENCE↗
Beam-recoil transferred polarization in $K^+Y$ electroproduction in the nucleon resonance region with CLAS12
We report beam-recoil transferred polarizations for the exclusive electroproduction of K + Λ and K + Σ 0 final states from an unpolarized proton target have been measured using the CLAS12 spectrometer at Jefferson Laboratory. The measurements at beam energies of 6.535 and 7.546 GeV span the range of four-momentum transfer Q 2 from 0.3 to 4.5 GeV 2 and invariant energy W from 1.6 to 2.4 GeV, while covering the full center-of-mass angular range of the K + . These new data extend the existing hyperon polarization data from CLAS in a similar kinematic range but from a significantly larger dataset. They represent an important addition to the world data, allowing for better exploration of the reaction mechanism in strangeness production processes, for further understanding of the spectrum and structure of excited nucleon states, and for improved insight into the strong interaction in the regime of nonperturbative dynamics.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Isospin dependence of Nucleon-Nucleon Short-range Correlations in Inclusive Scattering with Tritium and Helium-3
The nucleon-nucleon (NN) potential has a strong repulsive core. When a two-nucleon (sub)system falls into this range, they will interact strongly at short distance, and move away from each other with momenta above the Fermi level. This is called the NN Short range Correlations (SRCs). Previous experiments reported a neutron-proton pair (isos inglet) dominance in high-momentum nucleons. In inclusive electron scattering, this np dominance will cause a scaling behavior of cross sections at 1.4 < xbj = Q2/2m? < 2 where the high-momentum nucleons dominate. At Je?erson Lab Hall A we checked this hypothesis with electron Quasi-elastic (QE) scattering on A=3 nuclei systems. Our unique gas cell design made electron-tritium scattering possible for the ?rst time in a decade. The 2H, 3H, and 3He inclusive cross sections at 1 < xbj < 3 were measured in two experiments (E12-11-112 and E12-14-011) with a wide Q2 range (0.4 < Q2 < 3 GeV2). This thesis dis cusses the physics goals, experiment setup, and data analysis of the E12-11-112 experiment. Ratios of 3H/2H, 3He/2H and 3H/3He as well as absolute cross sections are presented at 0.4 < Q2 < 1.8 GeV2. NN SRC plateaus are observed in the cross section ratios at high Q2. The 3H/3He ratio of 0.84±0.01 at NN SRC dominant kinematics indicates a np to pp SRC pair ratio of 2.2±0.2 in A=3 nuclei. That implies a preference in T = 0 isospin singlet con?guration. No plateaus are observed at xbj > 2.
Li, Shujie↗
Advanced Ab Initio Methods for Nuclear Structure (Final Report)
Over the past decade, there has been enormous progress in the description of nuclear structure from first principles, using interactions from Chiral Effective Field Theory that are rooted in Quantum Chromodynamics, the fundamental theory of strong interactions, and many-body methods that solve the Schrödinger equation with systematically improvable approximations. Amongst those are the family of In-Medium Similarity Renormalization Group (IMSRG) framework developed by the PI and his co-workers. While these methods scale polynomially in the size N of the single-particle basis, computational efforts still grows dramatically as we increase the degrees of freedom for the nucleons by relaxing symmetries or introducing continuum couplings (see below), or as we push to improved truncations to provide precise inputs for experimental efforts, in particular in fundamental symmetry searches. In order to address this growing computational cost, one focus area of this award was the exploration of compression and factorization methods. The key to success or failure is the presence of low-rank structures within the matrix elements of NN and 3N interactions or the IMSRG evolution operator, and a means to reformulate the method that will let us exploit them.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗