jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Sinuhé Perea‐Puente | Francisco J. Rodríguez‐Fortuño
Source: arXiv (Cornell University) (preprint, 2023-07-07)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Complex refraction metasurfaces for locally enhanced propagation through opaque media Metasurfaces with linear phase gradients can redirect light beams. We propose controlling both phase and amplitude of a metasurface to extend Snell's law to the realm of complex angles, enabling a non-decaying transmission through opaque media with complex refractive indices. This leads to the discovery of non-diffracting and non-decaying solutions to the wave equation in opaque media, in the form of generalised cosine and Bessel-beams with a complex argument. While these solutions present nonphysical exponentially growing side tails, we address this via a windowing process, removing the side tails of the field profile while preserving significant transmission enhancement through an opaque slab on a small localized region. Such refined beam profiles may be synthesized by passive metasurfaces with phase and amplitude control at the opaque material's interface. Our findings, derived from rigorous solutions of the wave equation, promise new insights and enhanced control of light propagation in opaque media. Opacity ; Phase (matter) ; Optics ; Amplitude ; Physics ; Refraction ; Transmission (telecommunications) ; Snell's law ; Computer science ; Telecommunications Metamaterials and Metasurfaces Applications ; Orbital Angular Momentum in Optics ; Plasmonic and Surface Plasmon Research
Authors: Francis Berthias | Nurgül Bilgin | Jasmin Mecinović | Ole N. Jensen
Source:  (preprint, 2023-07-11)
Field: Chemistry — Spectroscopy

Top-down ion mobility/mass spectrometry reveals enzyme specificity: Separation and sequencing of isomeric proteoforms Enzymatic catalysis is one of the fundamental processes that drives the dynamic landscape of post-translational modifications (PTMs), expanding the structural and functional diversity of proteins. Here, we assessed enzyme specificity using a top-down ion mobility spectrometry (IMS) and tandem mass spectrometry (MS/MS) workflow. We successfully applied trapped IMS (TIMS) to investigate site-specific N-ε-acetylation of lysine residues of full-length histone H4 catalyzed by histone lysine acetyltransferase KAT8. We demonstrate that KAT8 exhibits a preference for N-ε-actylation of residue K16, while also installing N-ε-acetyl groups on residues K5 and K8 as the first degree of acetylation. Achieving TIMS resolving power values of up to 300, we fully separated mono-acetylated regioisomers (H4K5ac, H4K8ac, and H4K16ac). Each of these regioisomers produce unique MS/MS fragment ions, enabling estimation of their individual mobility distributions and the exact localization of the N-ε-acetylation sites. This study highlights the potential of top-down TIMS-MS/MS for conducting enzymatic assays at the intact protein level and, more generally, for separation and identification of isomeric proteoforms and precise PTM localization. Acetylation ; Lysine ; Ion-mobility spectrometry ; Chemistry ; Tandem mass spectrometry ; Mass spectrometry ; Histone ; Posttranslational modification ; Enzyme ; Histone acetyltransferase ; Acetyltransferase ; Ion ; Biochemistry ; Chromatography ; Combinatorial chemistry ; Amino acid ; DNA ; Organic chemistry Mass Spectrometry Techniques and Applications ; Advanced Proteomics Techniques and Applications ; RNA and protein synthesis mechanisms
Authors: Iana S. Chizhmakova | A.V. Nikitin | L. N. Sinit︠s︡a | V. I. Serdyukov | A. A. Lugovskoi | M. Rey | Vladimir G. Tyuterev
Source: Journal of Quantitative Spectroscopy and Radiative Transfer (article, 2023-04-20)
Field: Chemistry — Spectroscopy

Observation and analysis of ν1 + ν3 and ν1 + 2ν4 bands of CF4 molecule Ab initio ; Dipole ; Hamiltonian (control theory) ; Spectral line ; Atomic physics ; Ab initio quantum chemistry methods ; Fourier transform ; Molecule ; Infrared ; Physics ; Materials science ; Line (geometry) ; Molecular physics ; Nuclear magnetic resonance ; Optics ; Quantum mechanics ; Geometry Spectroscopy and Laser Applications ; Atmospheric Ozone and Climate ; Advanced Chemical Physics Studies
Authors: Yiwen Li | Zhengyan Zhu | Yongze Ye | Wenshan Hong | Yang Li | Shiliang Li | Huiqian Luo | Wen Hai‐Hu
Source: arXiv (Cornell University) (preprint, 2023-10-29)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Multiband superconductivity and a deep gap minimum from the specific heat in KCa$_2$(Fe$_{1-x}$Ni$_x$)$_4$As$_4$F$_2$ ($x$ = 0, 0.05, 0.13) Specific heat can explore low-energy quasiparticle excitations of superconductors, so it is a powerful tool for bulk measurement on the superconducting gap structure and pairing symmetry. Here, we report an in-depth investigation on the specific heat of the multiband superconductors KCa$_2$(Fe$_{1-x}$Ni$_x$)$_4$As$_4$F$_2$ ($x$ = 0, 0.05, 0.13) single crystals and the overdoped non-superconducting one with $x$ = 0.17. Clear specific heat anomalies can be observed at the superconducting transition temperature of 33.6 K and 28.8 K for the samples with $x$ = 0 and $x$ = 0.05, respectively. For the two samples, the magnetic field induced specific heat coefficient $Δγ(H)$ in the low-temperature limit increases rapidly below 2 T, then it rises slowly above 2 T. Using the non-superconducting sample with $x$ = 0.17 as a reference, the specific heat of phonon background for various superconducting samples can be obtained and subtracted, which allows us to extract the electronic specific heat of the superconducting samples. Through comparative analyses, it is found that the energy gap structure including two $s$-wave gaps and an extended $s$-wave gap with large anisotropy can reasonably describe the electronic specific heat data. According to these results, we suggest that at least one anisotropic superconducting gap with a deep gap minimum should exist in this multiband system. With the doping of Ni, the superconducting transition temperature of the sample decreases along with the decrease of the large $s$-wave gap, but the extended $s$-wave gap increases due to the enlarged electron pockets via adding more electrons. Despite these changes, the general properties of the gap structure remain unchanged versus doping Ni. Superconductivity ; Materials science ; Condensed matter physics ; Specific heat ; Band gap ; Chemistry ; Physics Iron-based superconductors research ; Inorganic Fluorides and Related Compounds ; Ferrocene Chemistry and Applications
Authors: Samuel P. Brown | Ryan J. Lawson | Jonathan D. Moreno | Joseph L. Ransdell
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2023-10-29)
Field: Chemistry — Electrochemistry

A Reinterpretation of the Relationship Between Persistent and Resurgent Sodium Currents The resurgent sodium current (I<sub>NaR</sub>) activates on membrane repolarization, such as during the downstroke of neuronal action potentials. Due to its unique activation properties, I<sub>NaR</sub> is thought to drive high rates of repetitive neuronal firing. However, I<sub>NaR</sub> is often studied in combination with the persistent or non-inactivating portion of sodium currents (I<sub>NaP</sub>). We used dynamic clamp to test how I<sub>NaR</sub> and I<sub>NaP</sub> individually affect repetitive firing in adult cerebellar Purkinje neurons from male and female mice. We learned I<sub>NaR</sub> does not scale repetitive firing rates due to its rapid decay at subthreshold voltages, and that subthreshold I<sub>NaP</sub> is critical in regulating neuronal firing rate. Adjustments to the Nav conductance model used in these studies revealed I<sub>NaP</sub> and I<sub>NaR</sub> can be inversely scaled by adjusting occupancy in the slow inactivated kinetic state. Together with additional dynamic clamp experiments, these data suggest the regulation of sodium channel slow inactivation can fine-tune I<sub>NaP</sub> and Purkinje neuron repetitive firing rates. Reinterpretation ; Economics ; Keynesian economics ; Physics Electrochemical Analysis and Applications ; Ion channel regulation and function ; Neuroscience and Neural Engineering
Authors: Santosh Neupane | Hong Tang | Adrienn Ruzsinszky
Source: arXiv (Cornell University) (preprint, 2023-02-21)
Field: Materials Science — Materials Chemistry

Defect-induced states, defect-induced phase transition and excitonic states in bent transition metal dichalcogenide (TMD) nanoribbons: density functional vs. many body theory Two-dimensional (2D) transition metal dichalcogenide (TMD) materials have versatile electronic and optical properties. TMD nanoribbons show interesting properties due to reduced dimensionality, quantum confinement, and edge states. Tang et al. showed that the edge bands evolved with bending can tune the optical properties for various widths of TMD nanoribbons. Defects are commonly present in 2D TMD materials, and can dramatically change the material properties. In this following work, we investigate the interaction between the edge and the defect states in WS2 nanoribbons with line defects under different bending conditions, using density functional theory (DFT). We reveal interesting semiconducting-to-metallic phase transitions, suggesting potential applications in nano-electronics or molecular electronics. We also calculate the optical absorption of the nanoribbons with different defect positions with the many-body GW-BSE (Bethe-Salpeter equation) approach, revealing a tunable optical spectrum and diverse exciton states in the defected TMD nanoribbons. Density functional theory ; Condensed matter physics ; Exciton ; Materials science ; Phase transition ; Bent molecular geometry ; Transition metal ; Nanotechnology ; Chemistry ; Physics ; Computational chemistry 2D Materials and Applications ; Graphene research and applications ; ZnO doping and properties
Authors: U. Munari
Source: arXiv (Cornell University) (preprint, 2023-07-01)
Field: Materials Science — Materials Chemistry

The "super-active" accretion phase of T CrB has ended The symbiotic recurrent nova T CrB erupted for the second and last recorded time in 1946. Following the outburst, the accretion rate onto its WD has remained rather low with only occasional and minor flaring episodes, until in late 2014 it entered a "super-active" phase (SAP) that peaked in April 2016: the flux radiated by Balmer lines increased by two orders of magnitude, accompanied by the appearance of strong HeI, HeII, and many other emission lines. Following the sharp maximum, the intensity of the emission lines has been steadily decreasing, reaching back the pre-SAP levels by mid-2023. The end of SAP is also confirmed by the drop of $B$-band brightness to pre-SAP conditions and the simultaneous re-appearance of a large-amplitude flickering. This suggest that the accretion disk has emptied from the extra material that has driven the "super active" state and has completed its transfer onto the WD, setting the stage for a new and probably imminent nova eruption. Balmer series ; Brightness ; Astrophysics ; Physics ; Amplitude ; Accretion disc ; Accretion (finance) ; Emission spectrum ; Nova (rocket) ; Phase (matter) ; Astronomy ; Spectral line ; Optics Diamond and Carbon-based Materials Research ; X-ray Spectroscopy and Fluorescence Analysis ; Ion-surface interactions and analysis
Authors: David T. S. Perkins | Aires Ferreira
Source: arXiv (Cornell University) (preprint, 2023-07-12)
Field: Materials Science — Materials Chemistry

Spintronics in 2D graphene-based van der Waals heterostructures Spintronics has become a broad and important research field that intersects with magnetism, nano-electronics, and materials science. Its overarching aim is to provide a fundamental understanding of spin-dependent phenomena in solid-state systems that can enable a new generation of spin-based logic devices. Over the past decade, graphene and related 2D van der Waals crystals have taken center stage in expanding the scope and potential of spintronic materials. Their distinctive electronic properties and atomically thin nature have opened new opportunities to probe and manipulate internal electronic degrees of freedom. Purely electrical control over conduction-electron spins can be attained in graphene-transition metal dichalcogenide heterostructures, due to proximity effects combined with graphene's high electronic mobility. Specifically, graphene experiences a proximity-induced spin-orbit coupling that enables efficient spin-charge interconversion processes; the two most well-known and at the forefront of current research are the spin Hall and inverse spin galvanic effects, wherein an electrical current yields a spin current and non-equilibrium spin polarization, respectively. This article provides an overview of the basic principles, theory, and experimental methods underpinning the nascent field of 2D material-based spintronics. Spintronics ; Graphene ; Nanotechnology ; Condensed matter physics ; van der Waals force ; Magnetism ; Nanoelectronics ; Materials science ; Heterojunction ; Physics ; Ferromagnetism ; Quantum mechanics Graphene research and applications ; 2D Materials and Applications ; Quantum and electron transport phenomena
Authors: S.C. Pradhan
Source: Journal of Aerospace Sciences and Technologies (article, 2023-08-01)
Field: Materials Science — Materials Chemistry

Buckling Analysis of Orthotropic Graphene Sheets Supported on Pasternak Elastic Medium Using Nonlocal Elasticity Theory and Differential Quadrature Method In this paper, the small scale effect on the buckling analysis of bi-axially compressed orthotropic Single-Layered Graphene Sheets (SLGS) supported on elastic medium is studied. Elastic theory of the graphene sheets is reformulated using the nonlocal differential constitutive relations of Eringen. Both Winkler-type and Pasternak-type foundation models are employed to simulate the interaction between the graphene sheet and supporting elastic medium. Using the principle of virtual work the governing differential equations are derived for rectangular orthotropic graphene sheets supported on elastic medium. Solutions for buckling loads for various boundary conditions are computed using Differential Quadrature Method (DQM). Parametric study has been performed to investigate the dependence of small scale effect on various graphene sheet parameters. It is observed that the nonlocal effect is significant in graphene sheets supported on elastic medium and has a decreasing effect on the buckling loads. Orthotropic material ; Graphene ; Buckling ; Nyström method ; Materials science ; Elasticity (physics) ; Boundary value problem ; Quadrature (astronomy) ; Parametric statistics ; Differential equation ; Mechanics ; Mathematical analysis ; Composite material ; Structural engineering ; Mathematics ; Physics ; Finite element method ; Optics ; Nanotechnology ; Engineering Nonlocal and gradient elasticity in micro/nano structures ; Composite Structure Analysis and Optimization ; Numerical methods in engineering
Authors: Gabriel Lazrak | Börge Göbel | A. Barthélémy | Ingrid Mertig | Annika Johansson | Manuel Bibès
Source: arXiv (Cornell University) (preprint, 2023-10-05)
Field: Materials Science — Materials Chemistry

Boosting the Edelstein effect of two-dimensional electron gases by ferromagnetic exchange Strontium titanate (SrTiO$_3$) two-dimensional electron gases (2DEGs) have broken spatial inversion symmetry and possess a finite Rashba spin-orbit coupling. This enables the interconversion of charge and spin currents through the direct and inverse Edelstein effects, with record efficiencies at low temperature, but more modest effects at room temperature. Here, we show that making these 2DEGs ferromagnetic enhances the conversion efficiency by nearly one order of magnitude. Starting from the experimental band structure of non-magnetic SrTiO$_3$ 2DEGs, we mimic magnetic exchange coupling by introducing an out-of-plane Zeeman term in a tight-binding model. We then calculate the band structure and spin textures for increasing internal magnetic fields and compute the Edelstein effect using a semiclassical Boltzmann approach. We find that the conversion efficiency first increases strongly with increasing magnetic field, then shows a maximum and finally decreases. This field dependence is caused by the competition of the exchange coupling with the effective Rashba interaction. While enhancing the splitting of band pairs amplifies the Edelstein effect, weakening the in-plane Rashba-type spin texture reduces it. Condensed matter physics ; Zeeman effect ; Point reflection ; Ferromagnetism ; Electron ; Semiclassical physics ; Magnetic field ; Physics ; Coupling (piping) ; Materials science ; Quantum mechanics ; Quantum Electronic and Structural Properties of Oxides ; Magnetic and transport properties of perovskites and related materials ; Quantum and electron transport phenomena
Authors: Wei Ren | Konstantin Davydov | Ziyan Zhu | Jaden Ma | Kenji Watanabe | Takashi Taniguchi | Efthimios Kaxiras | Mitchell Luskin | Ke Wang
Source: arXiv (Cornell University) (preprint, 2023-11-17)
Field: Materials Science — Materials Chemistry

Tunable Inter-Moiré Physics in Consecutively-Twisted Trilayer Graphene We fabricate a twisted trilayer graphene device with consecutive twist angles of 1.33 and 1.64 degrees, in which we electrostatically tune the electronic states from each of the two co-existing moiré superlattices and the interactions between them. When both moiré superlattices contribute equally to electrical transport, we report a new type of inter-moiré Hofstadter butterfly. Its Brown-Zak oscillation corresponds to one of the intermediate quasicrystal length scales of the reconstructed moiré of moiré (MoM) superlattice, shedding new light on emergent physics from competing atomic orders. Superlattice ; Moiré pattern ; Graphene ; Quasicrystal ; Condensed matter physics ; Twist ; Oscillation (cell signaling) ; Physics ; Materials science ; Optics ; Nanotechnology ; Geometry ; Chemistry Graphene research and applications ; Fullerene Chemistry and Applications ; 2D Materials and Applications
Authors: Jesse C. Hoke | Yifan Li | Julian May-Mann | Kenji Watanabe | Takashi Taniguchi | Barry Bradlyn | Taylor L. Hughes | Benjamin E. Feldman
Source: Research Square (preprint, 2023-10-02)
Field: Materials Science — Materials Chemistry

Uncovering the spin ordering in magic-angle graphene via edge state equilibration Condensed matter physics ; Physics ; Bilayer graphene ; Topological insulator ; Graphene ; Spin (aerodynamics) ; Magic angle ; Spin polarization ; Electron ; Quantum mechanics Graphene research and applications ; Quantum and electron transport phenomena ; Topological Materials and Phenomena
Authors: István Takács | Viktor Ivády
Source: arXiv (Cornell University) (preprint, 2023-09-07)
Field: Materials Science — Materials Chemistry

Accurate Hyperfine Tensors for Solid State Quantum Applications: Case of the NV Center in Diamond The decoherence of point defect qubits is often governed by the electron spin-nuclear spin hyperfine interaction that can be parameterized by using ab inito calculations in principle. So far most of the theoretical works have focused on the hyperfine interaction of the closest nuclear spins, while the accuracy of the predictions for distinct nuclear spins is barely discussed. We demonstrate for the case of the NV center in diamond that the absolute relative error of the computed hyperfine parameters can exceed 100\% in VASP for weakly coupled nuclear spins. To overcome this issue, we implement an alternative method and report on significantly improved hyperfine values with $O$(1\%) relative mean error at all distances. The provided accurate hyperfine data for the NV center enables high-precision simulation of NV quantum nodes for quantum information processing and positioning of nuclear spins by comparing experimental and theoretical hyperfine data. Hyperfine structure ; Spins ; Qubit ; Physics ; Quantum decoherence ; Diamond ; Atomic physics ; Spin (aerodynamics) ; Quantum information ; Quantum ; Quantum mechanics ; Condensed matter physics ; Chemistry Diamond and Carbon-based Materials Research ; High-pressure geophysics and materials ; Advanced Surface Polishing Techniques
Authors: A. V. Kotikov
Source: arXiv (Cornell University) (preprint, 2023-05-28)
Field: Materials Science — Materials Chemistry

Short review of interaction effects in graphene We review field theoretical studies dedicated to understanding the effects of electron-electron interaction in graphene, which is characterized by gapless bands, strong electron-electron interactions, and emerging Lorentz invariance deep in the infrared. We consider the influence of interactions on the transport properties of the system as well as their supposedly decisive influence on the potential dynamical generation of a gap. Graphene ; Gapless playback ; Physics ; Electron ; Condensed matter physics ; Lorentz transformation ; Field (mathematics) ; Theoretical physics ; Quantum mechanics ; Mathematics Graphene research and applications ; Quantum and electron transport phenomena ; Molecular Junctions and Nanostructures
Authors: Peter G. Velikanov | Н. П. Великанова | П. П. Иванов | Rafik Aliev
Source: E3S Web of Conferences (article, 2023-01-01)
Field: Materials Science — General Materials Science

Design optimization of the suspension unit of the liner in the combustion chamber housing The design of the suspension unit of the flame tube in the housing of the annular combustion chamber of a ground-based gas turbine installation of a gas pumping unit is given for placing it in a device for fixing the flame tube in the combustion chamber housing, where automatic clearance selection is required arising between the contacting surfaces of the docking nodes of the combustion chamber and the nozzle apparatus of the turbine, when the combustion chamber is operating as part of the engine. The proposed design of the suspension unit of the flame tube in the annular combustion chamber housing makes it possible to increase the reliability and resource of the combustion chamber and, in general, the entire ground-based gas turbine installation by eliminating the jamming of the split rings in the cups of the suspension units and the misalignment of the pushers relative to the suspension units and split support rings. Combustion chamber ; Nozzle ; Combustion ; Suspension (topology) ; Automotive engineering ; Nuclear engineering ; Tube (container) ; Mechanical engineering ; Materials science ; Engineering ; Waste management ; Environmental science ; Chemistry Material Properties and Applications ; Engineering Diagnostics and Reliability ; Advanced Power Generation Technologies