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An Extreme X-Ray Variability Event of a Weak-line Quasar (open access)

An Extreme X-Ray Variability Event of a Weak-line Quasar

Article reports the discovery of an extreme X-ray flux rise (by a factor of ≳20) of the weak-line quasar Sloan Digital Sky Survey (SDSS) J153913.47+395423.4 (hereafter SDSS J1539+3954) at z = 1.935. SDSS J1539+3954 is the most-luminous object among radio-quiet type 1 active galactic nuclei (AGNs) where such dramatic X-ray variability has been observed.
Date: February 3, 2020
Creator: Ni, Q.; Brandt, W. N.; Yi, W.; Luo, B.; Timlin, J. D., III; Hall, P. B. et al.
Object Type: Article
System: The UNT Digital Library
Development of a Thulium Fiber Laser for an Atomic Spectroscopy Experiment (open access)

Development of a Thulium Fiber Laser for an Atomic Spectroscopy Experiment

This article is a simplified analysis of a convenient thulium fiber laser source with 3 W of output power operating at a wavelength of 2059 nm with a slope efficiency of 49% with respect to input pump power and 60% with respect to absorbed pump power. The laser was applied in an atomic helium spectroscopy experiment to quench ³He (2058.63 nm) and ⁴He (2058.69 nm) meta-stable singlets (2¹S0), allowing for further investigation of the helium fine structure.
Date: February 15, 2020
Creator: Currey, Ronnie; Khademian, Ali & Shiner, David
Object Type: Article
System: The UNT Digital Library
Prescriptions for Correcting Ultraviolet-based Redshifts for Luminous Quasars at High Redshift (open access)

Prescriptions for Correcting Ultraviolet-based Redshifts for Luminous Quasars at High Redshift

This article presents near-infrared spectroscopy of 18 luminous quasars at 2.15 < z < 3.70 that allows the authors to obtain reliable systemic redshifts for these sources.
Date: April 8, 2020
Creator: Dix, Cooper; Shemmer, Ohad; Brotherton, Michael S.; Green, Richard F.; Mason, Michelle & Myers, Adam D.
Object Type: Article
System: The UNT Digital Library
Topological View of Flows Inside the BOLD Spontaneous Activity of the Human Brain (open access)

Topological View of Flows Inside the BOLD Spontaneous Activity of the Human Brain

Article describes study which found that persistent, recurring blood oxygen level dependent (BOLD) signals in triangulated rs-fMRI videoframes display previously undetected topological findings, i.e., vortex structures that cover brain activated regions.
Date: April 22, 2020
Creator: Don, Arjuna P. H.; Peters, James F.; Ramanna, Sheela & Tozzi, Arturo
Object Type: Article
System: The UNT Digital Library
High-Throughput Computational Search for Half-Metallic Oxides (open access)

High-Throughput Computational Search for Half-Metallic Oxides

The article describes a high-throughput computational search for half-metallic compounds. The analysis of calculated electronic properties of thousands of materials from the inorganic crystal structure database allowed the authors to identify potential half metals. They found over two-hundred strong half-metallic oxides; several of them have never been reported before.
Date: April 25, 2020
Creator: Liyanage, Laalitha S. I.; Slawińska, Jagoda; Gopal, Priya; Curtarolo, Stefano; Fornari, Marco & Buongiorno Nardelli, Marco
Object Type: Article
System: The UNT Digital Library
ALMA Observations of Quasar Host Galaxies at z ≃ 4.8 (open access)

ALMA Observations of Quasar Host Galaxies at z ≃ 4.8

Article presents ALMA Band 7 data of the [C ıı] 𝜆157.74 𝜇m emission line and underlying far-IR (FIR) continuum for 12 luminous quasars at 𝓏 ≃ 4.8 powered by fast-growing supermassive black holes (SMBHs).
Date: May 27, 2020
Creator: Shemmer, Ohad; Nguyen, Nathen H.; Lira, Paulina; Trakhtenbrot, Benny; Netzer, Hagai; Cicone, Claudia et al.
Object Type: Article
System: The UNT Digital Library
Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact (open access)

Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact

Article investigating ionization of atomic hydrogen by electron- and positron-impact. This article belongs to the Special Issue: Interactions of Positrons with Matter and Radiation.
Date: May 29, 2020
Creator: DeMars, C. M.; Ward, S. J.; Colgan, J.; Amami, S. & Madison, D. H.
Object Type: Article
System: The UNT Digital Library
Role of quantum confinement and interlayer coupling in CrI3-graphene magnetic tunnel junctions (open access)

Role of quantum confinement and interlayer coupling in CrI3-graphene magnetic tunnel junctions

Article presents a combination of first principles and quantum ballistic transport calculations to shed important insights from an atomistic viewpoint on the underlying mechanisms governing spin transport in graphene/ CrI₃ junctions.
Date: May 29, 2020
Creator: Buongiorno Nardelli, Marco; Heath, Jonathan J.; Costa, Marcio & Kuroda, Marcelo A.
Object Type: Article
System: The UNT Digital Library
Phononic crystal as a homogeneous viscous metamaterial (open access)

Phononic crystal as a homogeneous viscous metamaterial

Article develops a homogenization theory, representing the low-frequency limit for a phononic crystal of cylinders embedded in a viscous fluid.
Date: June 8, 2020
Creator: Krokhin, Arkadii A.; Zubov, Yu.; Ibarias, M. & Arriaga, J.
Object Type: Article
System: The UNT Digital Library
Closed-form expressions for the magnetic fields of rectangular and circular finite-length solenoids and current loops (open access)

Closed-form expressions for the magnetic fields of rectangular and circular finite-length solenoids and current loops

This article discusses closed-form expressions for the magnetic fields produced by rectangular- and circular-shaped finite-length solenoids and current loops. The closed-form expression for the magnetic field of a rectangular-shaped finite-length solenoid is derived using the Biot–Savart law. Closed-form expressions for the magnetic fields of solenoids and current loops can be used to avoid approximations in analytical models and may reduce computation time in computer simulations.
Date: June 15, 2020
Creator: Hampton, S.; Lane, R. A.; Hedlof, R. M.; Phillips, R. E. & Ordonez, Carlos A.
Object Type: Article
System: The UNT Digital Library
Multitask deep-learning-based design of chiral plasmonic metamaterials (open access)

Multitask deep-learning-based design of chiral plasmonic metamaterials

This article presents an end-to-end functional bidirectional deep-learning (DL) model for three-dimensional chiral metamaterial design and optimization. This ML model utilizes multitask joint learning features to recognize, generalize, and explore in detail the nontrivial relationship between the metamaterials’ geometry and their chiroptical response, eliminating the need for auxiliary networks or equivalent approaches to stabilize the physically relevant output. This model efficiently realizes both forward and inverse retrieval tasks with great precision, offering a promising tool for iterative computational design tasks in complex physical systems. Other potential applications include photodetectors, polarization-resolved imaging, and circular dichroism (CD) spectroscopy.
Date: July 1, 2020
Creator: Ashalley, Eric; Acheampong, Kingsley; Besteiro, Lucas V.; Yu, Peng; Neogi, Arup; Govorov, Alexander O. et al.
Object Type: Article
System: The UNT Digital Library
Long-range nonspreading propagation of sound beam through periodic layered structure (open access)

Long-range nonspreading propagation of sound beam through periodic layered structure

Article analyzing dispersion of sound in a solid-fluid layered structure and found a flex point on the isofrequency curve where D vanishes for given direction of propagation and frequency. Nonspreading propagation is experimentally observed in a water steel lattice of 75 periods (~1 meter long) and occurs in the regime of anomalous dispersion and strong acoustic anisotropy when the effective mass along periodicity is close to zero. Under these conditions the incoming beam experiences negative refraction of phase velocity leading to backward wave propagation. The observed effect is explained using a complete set of dynamical equations and our effective medium theory.
Date: September 2, 2020
Creator: Zubov, Yurii; Djafari-Rouhani, Bahram; Jin, Yuqi; Sofield, Mathew; Walker, Ezekiel; Neogi, Arup et al.
Object Type: Article
System: The UNT Digital Library
Anisotropic Optical Properties of 2D Silicon Telluride (open access)

Anisotropic Optical Properties of 2D Silicon Telluride

Article reports an ab initio computational study of the optical dielectric properties of Silicon telluride (Si2Te3) using the GW approximation and the Bethe-Salpeter equation (BSE).
Date: September 27, 2020
Creator: Cui, Jingbiao; Bhattarai, Romakanta; Chen, Jiyang; Hoang, Thang B. & Shen, Xiao
Object Type: Article
System: The UNT Digital Library
Anisotropic optical properties of single Si2Te3 nanoplates (open access)

Anisotropic optical properties of single Si2Te3 nanoplates

Article reporting a combined experimental and computational study of the optical properties of individual silicon telluride (Si2Te3) nanoplates.
Date: November 5, 2020
Creator: Chen, Jiyang; Bhattarai, Romakanta; Cui, Jingbiao; Shen, Xiao & Hoang, Thang
Object Type: Article
System: The UNT Digital Library
Sub-wavelength lateral detection of tissue-approximating masses using an ultrasonic metamaterial lens (open access)

Sub-wavelength lateral detection of tissue-approximating masses using an ultrasonic metamaterial lens

Article demonstrating a phononic metamaterial lens (ML) for detection of laterally subwavelength object features in tissue-like phantoms beyond the phononic crystal evanescent zone and Fresnel zone of the emitter.
Date: November 24, 2020
Creator: Walker, Ezekiel; Jin, Yuqi; Reyes, Delfino & Neogi, Arup
Object Type: Article
System: The UNT Digital Library
Using a Novel Approach to Estimate Packing Density and Related Electrical Resistance in Multiwall Carbon Nanotube Networks (open access)

Using a Novel Approach to Estimate Packing Density and Related Electrical Resistance in Multiwall Carbon Nanotube Networks

Article using contrast image processing to estimate the concentration of multi-wall carbon nanotubes (MWCNT) in a given network.
Date: September 25, 2020
Creator: Philipose, Usha; Jiang, Yan; Farmer, Gavin; Howard, Chris; Harcrow, Michael; Littler, Chris et al.
Object Type: Article
System: The UNT Digital Library
Dielectric function of six elemental metals (open access)

Dielectric function of six elemental metals

This article presents an accurate first-principles study of the electronic structure and absorption spectrum of six elemental metals (aluminium, gold, silver, copper, palladium, platinum) using density functional theory in an all-electron full-potential framework.
Date: December 2020
Creator: Pogodaeva, Maria K.; Levchenko, Sergey; Drachev, Vladimir P. & Gabitov, Ildar R.
Object Type: Article
System: The UNT Digital Library
Magnetic confinement of effectively unmagnetized plasma particles (open access)

Magnetic confinement of effectively unmagnetized plasma particles

Article develops a planar model for an artificially structured boundary that may provide magnetic confinement of nonmagnetically trapped plasma particles.
Date: December 1, 2020
Creator: Ordonez, Carlos A.
Object Type: Article
System: The UNT Digital Library
Surface-specific washing-free immunosensor for time-resolved cortisol monitoring (open access)

Surface-specific washing-free immunosensor for time-resolved cortisol monitoring

This article describes a method of measuring cortisol levels. It presents a metal-enhanced fluorescence assay based on a displacement of a dye labeled BSA-cortisol conjugate from the immune complex immobilized on the golden islands by free cortisol.
Date: December 29, 2020
Creator: Safarian, Sofia M.; Kusov, Pavel A.; Kosolobov, Sergey S.; Borzenkova, Oksana V.; Khakimov, Artem V.; Kotelevtsev, Yuri V. et al.
Object Type: Article
System: The UNT Digital Library
Disentangling Orbital and Valley Hall Effects in Bilayers of Transition Metal Dichalcogenides (open access)

Disentangling Orbital and Valley Hall Effects in Bilayers of Transition Metal Dichalcogenides

This article shows that a bilayer of 2H-MoS₂ is an orbital Hall insulator that exhibits a sizeable orbital Hall effect in the absence of both spin and valley Hall effects. The results are based on density functional theory and low-energy effective model calculations and strongly suggest that bilayers of TMDs are highly suitable platforms for direct observation of the orbital Hall insulating phase in two-dimensional materials.
Date: February 5, 2021
Creator: Cysne, Tarik P.; Costa, Marcio; Canonico, Luis M.; Buongiorno Nardelli, Marco; Muniz, R. B. & Rappoport, Tatiana G.
Object Type: Article
System: The UNT Digital Library
Discovery of higher-order topological insulators using the spin Hall conductivity as a topology signature (open access)

Discovery of higher-order topological insulators using the spin Hall conductivity as a topology signature

This article shows a connection between spin Hall effect and HOTIs using a combination of ab initio calculations and tight-binding modeling. The model demonstrates how a non-zero bulk midgap spin Hall conductivity (SHC) emerges within the HOTI phase. This work guides novel experimental and theoretical advances towards higher-order topological insulator realization and applications.
Date: April 12, 2021
Creator: Costa, Marcio; Mera Acosta, Carlos; Padilha, Antonio C.M.; Cerasoli, Frank T.; Buongiorno Nardelli, Marco & Fazzio, Adalberto
Object Type: Article
System: The UNT Digital Library
Topologically driven linear magnetoresistance in helimagnetic FeP (open access)

Topologically driven linear magnetoresistance in helimagnetic FeP

Article presenting a series of high magnetic field experiments on high-quality single crystals of FeP. The study shows that resistance not only increases without saturation by up to several hundred times its zero-field value by 35 T, but that it also exhibits an anomalously linear field dependence over the entire range when the field is aligned precisely along the crystallographic c-axis.
Date: April 14, 2021
Creator: Campbell, D.J.; Collini, J.; Sławińska, Jagoda; Autieri, C.; Wang, L.; Wang, K. et al.
Object Type: Article
System: The UNT Digital Library
Ultrafast dephasing in hydrogen-bonded pyridine–water mixtures (open access)

Ultrafast dephasing in hydrogen-bonded pyridine–water mixtures

Article studying Hydrogen-bonded pyridine–water mixtures by a time-frequency resolved coherent Raman spectroscopic technique.
Date: May 4, 2021
Creator: Ariunbold, Gombojav O.; Semon, Bryan; Nagpal, Supriya & Rostovtsev, Yuri V.
Object Type: Article
System: The UNT Digital Library
Do gene-environment interactions play a role in COVID-19 distribution? The case of Alpha-1 Antitrypsin, air pollution and COVID-19 (open access)

Do gene-environment interactions play a role in COVID-19 distribution? The case of Alpha-1 Antitrypsin, air pollution and COVID-19

This article evaluates the role that gene-environment interaction between air-pollution and Alpha-1 Antitrypsin (AAT) genes plays in the severity of COVID-19. Results find parallelism between the number of COVID deaths and the AAT*air pollution global risk in Europe.
Date: May 7, 2021
Creator: Murgia, Nicola; Corsico, Angelo Guido; D'Amato, Gennaro; Maesano, Cara Nichole; Tozzi, Arturo & Annesi-Maesano, Isabella
Object Type: Article
System: The UNT Digital Library