46,561 results match your criteria Astronomy & Geophysics[Journal]

Adsorption of Lanthanide Atoms on Graphene: Similar, Yet Different.

J Phys Chem Lett 2022 Jun 24:6042-6047. Epub 2022 Jun 24.

Instituto de Ciencias Aplicadas y Technología, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 Cd. México, Mexico.

Many theoretical studies address the interaction of different atoms with graphene; however, the relevant information on the adsorption of the lanthanide species remains limited and controversial, creating a gap in this important area of graphene chemistry and physics. By employing periodic density functional theory calculations, we provide the key theoretical information for the entire series from lanthanum to lutetium interacting with defect-free graphene, including the interaction strength and distances, charge and spin of the lanthanide atoms, and comparative features of the density of states. The central lanthanides Gd, Tb, and Dy exhibit the strongest bonding and shortest distances. Read More

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Optical suppression of energy barriers in single molecule-metal binding.

Sci Adv 2022 Jun 24;8(25):eabp9285. Epub 2022 Jun 24.

Nanophotonics Centre, Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, England, UK.

Transient bonds between molecules and metal surfaces underpin catalysis, bio/molecular sensing, molecular electronics, and electrochemistry. Techniques aiming to characterize these bonds often yield conflicting conclusions, while single-molecule probes are scarce. A promising prospect confines light inside metal nanogaps to elicit in operando vibrational signatures through surface-enhanced Raman scattering. Read More

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Stress-induced high- superconductivity in solid molecular hydrogen.

Proc Natl Acad Sci U S A 2022 Jun 24;119(26):e2122691119. Epub 2022 Jun 24.

Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154.

Solid molecular hydrogen has been predicted to be metallic and high-temperature superconducting at ultrahigh hydrostatic pressures that push current experimental limits. Meanwhile, little is known about the influence of nonhydrostatic conditions on its electronic properties at extreme pressures where anisotropic stresses are inevitably present and may also be intentionally introduced. Here we show by first-principles calculations that solid molecular hydrogen compressed to multimegabar pressures can sustain large anisotropic compressive or shear stresses that, in turn, cause major crystal symmetry reduction and charge redistribution that accelerate bandgap closure and promote superconductivity relative to pure hydrostatic compression. Read More

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Spontaneous Formation of Time-Periodic Vortex Cluster in Nonlinear Fluids of Light.

Phys Rev Lett 2022 Jun;128(23):237402

Hybrid Photonics Laboratory, Skolkovo Institute of Science and Technology, Territory of Innovation Center Skolkovo, Bolshoy Boulevard 30, Building 1, 121205 Moscow, Russia.

We demonstrate spontaneous formation of a nonlinear vortex cluster state in a microcavity exciton-polariton condensate with time-periodic sign flipping of its topological charges at the GHz scale. When optically pumped with a ring-shaped nonresonant laser, the trapped condensate experiences intricate high-order mode competition and fractures into two distinct trap levels. The resulting mode interference leads to robust condensate density beatings with periodic appearance of orderly arranged phase singularities. Read More

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Ab Initio Simulation of Amorphous Graphite.

Phys Rev Lett 2022 Jun;128(23):236402

Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA.

An amorphous graphite material has been predicted from molecular dynamics simulation using ab initio methods. Carbon materials reveal a strong proclivity to convert into a sp^{2} network and then layer at temperatures near 3000 K within a density range of ca. 2. Read More

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Critical Lattice Model for a Haagerup Conformal Field Theory.

Phys Rev Lett 2022 Jun;128(23):231602

Department of Physics and Astronomy, Ghent University, Krijgslaan 281, S9, B-9000 Ghent, Belgium.

We use the formalism of strange correlators to construct a critical classical lattice model in two dimensions with the Haagerup fusion category H_{3} as input data. We present compelling numerical evidence in the form of finite entanglement scaling to support a Haagerup conformal field theory (CFT) with central charge c=2. Generalized twisted CFT spectra are numerically obtained through exact diagonalization of the transfer matrix, and the conformal towers are separated in the spectra through their identification with the topological sectors. Read More

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Scattering Searches for Dark Matter in Subhalos: Neutron Stars, Cosmic Rays, and Old Rocks.

Phys Rev Lett 2022 Jun;128(23):231801

TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.

In many cosmologies dark matter clusters on subkiloparsec scales and forms compact subhalos, in which the majority of Galactic dark matter could reside. Null results in direct detection experiments since their advent four decades ago could then be the result of extremely rare encounters between the Earth and these subhalos. We investigate alternative and promising means to identify subhalo dark matter interacting with standard model particles: (1) subhalo collisions with old neutron stars can transfer kinetic energy and brighten the latter to luminosities within the reach of imminent infrared, optical, and ultraviolet telescopes; we identify new detection strategies involving single-star measurements and Galactic disk surveys, and obtain the first bounds on self-interacting dark matter in subhalos from the coldest known pulsar, PSR J2144-3933; (2) subhalo dark matter scattering with cosmic rays results in detectable effects; (3) historic Earth-subhalo encounters can leave dark matter tracks in Paleolithic minerals deep underground. Read More

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Properties of Daily Helium Fluxes.

Phys Rev Lett 2022 Jun;128(23):231102

Shandong Institute of Advanced Technology (SDIAT), Jinan, Shandong 250100, China.

We present the precision measurement of 2824 daily helium fluxes in cosmic rays from May 20, 2011 to October 29, 2019 in the rigidity interval from 1.71 to 100 GV based on 7.6×10^{8} helium nuclei collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. Read More

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Results from the Baksan Experiment on Sterile Transitions (BEST).

Phys Rev Lett 2022 Jun;128(23):232501

JSC "State Scientific Center Research Institute of Atomic Reactors," Dimitrovgrad 433510, Russia.

The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate the deficit of electron neutrinos ν_{e} observed in previous gallium-based radiochemical measurements with high-intensity neutrino sources, commonly referred to as the "gallium anomaly," which could be interpreted as evidence for oscillations between ν_{e} and sterile neutrino (ν_{s}) states. A 3.414-MCi ^{51}Cr ν_{e} source was placed at the center of two nested Ga volumes and measurements were made of the production of ^{71}Ge through the charged current reaction, ^{71}Ga(ν_{e},e^{-})^{71}Ge, at two average distances. Read More

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The Phylogeny of Rays and Skates (Chondrichthyes: Elasmobranchii) Based on Morphological Characters Revisited.

Diversity (Basel) 2022 Jun;14(6):456

Evolutionary Morphology Research Group, Department of Palaeontology, Faculty of Earth Sciences, Geography and Astronomy, University of Vienna, Josef-Holaubek-Platz 2,1090 Vienna, Austria.

Elasmobranchii are relatively well-studied. However, numerous phylogenetic uncertainties about their relationships remain. Here, we revisit the phylogenetic evidence based on a detailed morphological re-evaluation of all the major extant batomorph clades (skates and rays), including several holomorphic fossil taxa from the Palaeozoic, Mesozoic and Cenozoic, and an extensive outgroup sampling, which includes sharks, chimaeras and several other fossil chondrichthyans. Read More

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studies of ASEM analogues targeting α7-nAChR and experimental verification.

RSC Adv 2021 Jan 21;11(7):3942-3951. Epub 2021 Jan 21.

Department of Physics and Astronomy, Uppsala University Box 516 SE-751 20 Uppsala Sweden.

The α7 nicotinic acetylcholine receptor (α7-nAChR) is implicated in a variety of neurodegenerative and neuropsychiatric disorders, such as Alzheimer's disease (AD) and schizophrenia. The progress of these disorders can be studied using positron emission tomography (PET) with radiotracers for α7-nAChR. [F]ASEM and [F] -ASEM (also referred to as [F]DBT-10) are novel and potent α7-nAChR PET radiotracers which have successfully been used in human subjects and nonhuman primates, though further improvement of them is still a pressing task in the community of neurodegeneration research. Read More

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January 2021

Bidirectional Effect of Repeated Exposure to Extremely Low-Frequency Electromagnetic Field (50 Hz) of 1 and 7 mT on Oxidative/Antioxidative Status in Rat's Brain: The Prediction for the Vulnerability to Diseases.

Oxid Med Cell Longev 2022 14;2022:1031211. Epub 2022 Jun 14.

Department of Animal Physiology and Neurobiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100, Poland.

Studies reported evidence for opposite effects of extremely low-frequency electromagnetic field (EMF): harmful, including the oxidative stress induction, and beneficial, such as the activation of antioxidant defense. People's exposure to EMF is often repeated or prolonged, and it is important to consider the cumulative effect of such kind of exposure on the organism. If changes evoked by repeated exposure to EMF are permanent, responsiveness to other stress factors can be modified. Read More

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Organic Electrochemical Transistors as Versatile Tool for Real-Time and Automatized Viral Cytopathic Effect Evaluation.

Viruses 2022 May 26;14(6). Epub 2022 May 26.

Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Universtity of Bologna, 40138 Bologna, Italy.

In-vitro viral studies are still fundamental for biomedical research since studying the virus kinetics on cells is crucial for the determination of the biological properties of viruses and for screening the inhibitors of infections. Moreover, testing potential viral contaminants is often mandatory for safety evaluation. Nowadays, viral cytopathic effects are mainly evaluated through end-point assays requiring dye-staining combined with optical evaluation. Read More

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A Simple Optical Sensor Based on Multimodal Interference Superimposed on Additive Manufacturing for Diameter Measurement.

Sensors (Basel) 2022 Jun 17;22(12). Epub 2022 Jun 17.

Institute for Systems and Computer Engineering, Technology and Science, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.

In many areas, the analysis of a cylindrical structure is necessary, and a form to analyze it is by evaluating the diameter changes. Some areas can be cited: pipelines for oil or gas distribution and radial growth of trees whose diameter changes are directly related to irrigation and the radial expansion since it depends on the water soil deficit. For some species, these radial variations can change in around 5 mm. Read More

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Hydrodynamic and Polyelectrolyte Properties of Actin Filaments: Theory and Experiments.

Polymers (Basel) 2022 Jun 16;14(12). Epub 2022 Jun 16.

Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, TX 78249, USA.

Actin filament's polyelectrolyte and hydrodynamic properties, their interactions with the biological environment, and external force fields play an essential role in their biological activities in eukaryotic cellular processes. In this article, we introduce a unique approach that combines dynamics and electrophoresis light-scattering experiments, an extended semiflexible worm-like chain model, and an asymmetric polymer length distribution theory to characterize the polyelectrolyte and hydrodynamic properties of actin filaments in aqueous electrolyte solutions. A fitting approach was used to optimize the theories and filament models for hydrodynamic conditions. Read More

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Source Attribution of Human Campylobacteriosis Using Whole-Genome Sequencing Data and Network Analysis.

Pathogens 2022 Jun 3;11(6). Epub 2022 Jun 3.

Research Group for Genomic Epidemiology, National Food Institute, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.

spp. are a leading and increasing cause of gastrointestinal infections worldwide. Source attribution, which apportions human infection cases to different animal species and food reservoirs, has been instrumental in control- and evidence-based intervention efforts. Read More

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Electro-Sorption of Hydrogen by Platinum, Palladium and Bimetallic Pt-Pd Nanoelectrode Arrays Synthesized by Pulsed Laser Ablation.

Micromachines (Basel) 2022 Jun 18;13(6). Epub 2022 Jun 18.

Department of Physics and Astronomy "Ettore Majorana", University of Catania, Via Santa Sofia 64, 95123 Catania, Italy.

Sustainable and renewable production of hydrogen by water electrolysers is expected to be one of the most promising methods to satisfy the ever-growing demand for renewable energy production and storage. Hydrogen evolution reaction in alkaline electrolyte is still challenging due to its slow kinetic properties. This study proposes new nanoelectrode arrays for high Faradaic efficiency of the electro-sorption reaction of hydrogen in an alkaline electrolyte. Read More

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Optimizing Broadband Near-Infrared Emission in Bi/Sn-Doped Aluminosilicate Glass by Modulating Glass Composition.

Micromachines (Basel) 2022 Jun 10;13(6). Epub 2022 Jun 10.

Sichuan Hetai Optical Fiber Co., Ltd., Nanchong 637002, China.

The Bi/Sn-doped aluminosilicate glass samples were prepared using a melting-quenching method and their near-infrared (NIR) emission properties were studied. An ultra-broadband NIR emission ranging from 950 nm to 1600 nm was observed in all samples under 480 nm excitation, which covered the whole fiber low-loss window. The NIR emission spectrum showed that the maximum emission peak was about 1206 nm and the full width at half maximum (FWHM) was about 220 nm. Read More

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Effect of Gamma Irradiation on the Structural, Optical, Electrical, and Ferroelectric Characterizations of Bismuth-Modified Barium Titanate Ceramics.

Materials (Basel) 2022 Jun 19;15(12). Epub 2022 Jun 19.

Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.

Materials with ferroelectric properties, low bandgap energies, high polarization, low loss, and thermal stability are essential for future solar-cell applications. Researchers have attempted to obtain such materials by using several approaches. In this vein, a novel approach is reported in this work using gamma ray irradiation. Read More

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Assessment of Alkali-Silica Reaction Potential in Aggregates from Iran and Australia Using Thin-Section Petrography and Expansion Testing.

Materials (Basel) 2022 Jun 17;15(12). Epub 2022 Jun 17.

School of Engineering, Macquarie University, Sydney, NSW 2109, Australia.

The alkali-silica reaction can shorten concrete life due to expansive pressure build-up caused by reaction by-products, resulting in cracking. Understanding the role of the aggregate, as the main reactive component, is essential for understanding the underlying mechanisms of the alkali-silica reaction and thereby reducing, or even preventing, any potential damage. The present study aims to investigate the role of petrographic studies along with accelerated tests in predicting and determining the potential reactivity of aggregates, including granite, rhyodacite, limestone, and dolomite, with different geological characteristics in concrete. Read More

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Pressure-Dependent Structure of BaZrO Crystals as Determined by Raman Spectroscopy.

Materials (Basel) 2022 Jun 17;15(12). Epub 2022 Jun 17.

Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea.

The structure of dielectric perovskite BaZrO, long known to be cubic at room temperature without any structural phase transition with variation in temperature, has been recently disputed to have different ground state structures with lower symmetries involving octahedra rotation. Pressure-dependent Raman scattering measurements can identify the hierarchy of energetically-adjacent polymorphs, helping in turn to understand its ground state structure at atmospheric pressure. Here, the Raman scattering spectra of high-quality BaZrO single crystals grown by the optical floating zone method are investigated in a pressure range from 1 atm to 42 GPa. Read More

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Continuous Goos-Hänchen Shift of Vortex Beam via Symmetric Metal-Cladding Waveguide.

Materials (Basel) 2022 Jun 16;15(12). Epub 2022 Jun 16.

Department of Physics and Astronomy, Shanghai JiaoTong University, Shanghai 200240, China.

Goos-Hänchen shift provides a way to manipulate the transverse shift of an optical beam with sub-wavelength accuracy. Among various enhancement schemes, millimeter-scale shift at near-infrared range has been realized by a simple symmetrical metal-cladding waveguide structure owing to its unique ultrahigh-order modes. However, the interpretation of the shift depends crucially on its definition. Read More

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Editorial to the Special Issue "Molecular Motors: From Single Molecules to Cooperative and Regulatory Mechanisms In Vivo".

Int J Mol Sci 2022 Jun 14;23(12). Epub 2022 Jun 14.

Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy.

The Molecular motors or motor proteins are able to generate force and do mechanical work that is used to displace a load or produce relative movements between molecules or macromolecular assembles [... Read More

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Gamow Temperature in Tsallis and Kaniadakis Statistics.

Entropy (Basel) 2022 Jun 8;24(6). Epub 2022 Jun 8.

Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), University of Maragheh, Maragheh P.O. Box 55136-553, Iran.

Relying on the quantum tunnelling concept and Maxwell-Boltzmann-Gibbs statistics, Gamow shows that the star-burning process happens at temperatures comparable to a critical value, called the Gamow temperature (T) and less than the prediction of the classical framework. In order to highlight the role of the equipartition theorem in the Gamow argument, a thermal length scale is defined, and then the effects of non-extensivity on the Gamow temperature have been investigated by focusing on the Tsallis and Kaniadakis statistics. The results attest that while the Gamow temperature decreases in the framework of Kaniadakis statistics, it can be bigger or smaller than T when Tsallis statistics are employed. Read More

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Individual differences in frontoparietal plasticity in humans.

NPJ Sci Learn 2022 Jun 23;7(1):14. Epub 2022 Jun 23.

Department of Psychology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA.

Neuroplasticity, defined as the brain's potential to change in response to its environment, has been extensively studied at the cellular and molecular levels. Work in animal models suggests that stimulation to the ventral tegmental area (VTA) enhances plasticity, and that myelination constrains plasticity. Little is known, however, about whether proxy measures of these properties in the human brain are associated with learning. Read More

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The obligate intracellular bacterium Orientia tsutsugamushi differentiates into a developmentally distinct extracellular state.

Nat Commun 2022 Jun 23;13(1):3603. Epub 2022 Jun 23.

Public Health Research Institute, Rutgers the State University of New Jersey, Newark, NJ, USA.

Orientia tsutsugamushi (Ot) is an obligate intracellular bacterium in the family Rickettsiaceae that causes scrub typhus, a severe mite-borne human disease. Its mechanism of cell exit is unusual amongst Rickettsiaceae, as Ot buds off the surface of infected cells enveloped in plasma membrane. Here, we show that Ot bacteria that have budded out of host cells are in a distinct developmental stage compared with intracellular bacteria. Read More

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Interactions between copper homeostasis and the fungal cell wall affect copper stress resistance.

PLoS Pathog 2022 Jun 23;18(6):e1010195. Epub 2022 Jun 23.

Duke University School of Medicine, Departments of Medicine, Durham, North Carolina, United States of America.

Copper homeostasis mechanisms are essential for microbial adaption to changing copper levels within the host during infection. In the opportunistic fungal pathogen Cryptococcus neoformans (Cn), the Cn Cbi1/Bim1 protein is a newly identified copper binding and release protein that is highly induced during copper limitation. Recent studies demonstrated that Cbi1 functions in copper uptake through the Ctr1 copper transporter during copper limitation. Read More

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The effect of discrete wavelengths of visible light on the developing murine embryo.

J Assist Reprod Genet 2022 Jun 23. Epub 2022 Jun 23.

School of Biomedicine, Robinson Research Institute, The University of Adelaide, Adelaide, SA, 5005, Australia.

Purpose: A current focus of the IVF field is non-invasive imaging of the embryo to quantify developmental potential. Such approaches use varying wavelengths to gain maximum biological information. The impact of irradiating the developing embryo with discrete wavelengths of light is not fully understood. Read More

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Host cell RecA activates a mobile element-encoded mutagenic DNA polymerase.

Nucleic Acids Res 2022 Jun 23. Epub 2022 Jun 23.

Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.

Homologs of the mutagenic Escherichia coli DNA polymerase V (pol V) are encoded by numerous pathogens and mobile elements. We have used Rum pol (RumA'2B), from the integrative conjugative element (ICE), R391, as a model mobile element-encoded polymerase (MEPol). The highly mutagenic Rum pol is transferred horizontally into a variety of recipient cells, including many pathogens. Read More

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