We determine the form of the complex shear modulus G* in soft sphere packings near jamming. Viscoelastic response at finite frequency is closely tied to a packing's intrinsic relaxational modes, which are distinct from the vibrational modes of undamped packings. We demonstrate and explain the appearance of an anomalous excess of slowly relaxing modes near jamming, reflected in a diverging relaxational density of states. From the density of states, we derive the dependence of G* on the frequency and distance to the jamming transition, which is confirmed by numerics.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1103/PhysRevLett.107.158303 | DOI Listing |
Ann Nucl Med
January 2025
Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
Dynamic positron emission tomography (PET) can be used to non-invasively estimate the blood flow of different organs via compartmental modeling. Out of different PET tracers, water labeled with the radioactive O isotope of oxygen (half-life of 2.04 min) is freely diffusable, and therefore, very well-suited for blood flow quantification.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
KU Leuven, Materials engineering, Kasteelpark Arenberg 44 bus 2450, 3001 LEUVEN Belgium, LEUVEN, BELGIUM.
Traditional polymer solid electrolytes (PSEs) suffer from low Li conductivity, poor kinetics and safety concerns. Here, we present a novel porous MOF glass gelled polymer electrolyte (PMG-GPE) prepared via a top-down strategy, which features a unique three-dimensional interconnected graded-aperture structure for efficient ion transport. Comprehensive analyses, including time-of-flight secondary ion mass spectrometry (TOF-SIMS), Solid-state 7Li magic-angle-spinning nuclear magnetic resonance (MAS-NMR), Molecular Dynamics (MD) simulations, and electrochemical tests, quantify the pore structures, revealing their relationship with ion conductivity that increases and then decreases as macropore proportion rises.
View Article and Find Full Text PDFNanoscale
January 2025
School of Chemistry, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.
Engineering the local electronic structure of single atom catalysts (SACs) still remains challenging. In this study, a Ru-NiS single atom catalyst with a controlled S coordination environment, where Ru single atoms are implanted on a NiS nanoflower consisting of plenty of cross-linked nanosheets, has been developed a facile atom capture strategy. Using Density Functional Theory (DFT) calculations, it has been revealed that the fine-tuned local S coordination environment can optimize the electronic structure of Ru active sites, and reduce the energy barrier of the rate-determining step for the oxygen evolution reaction (OER), thus boosting the electrocatalytic activity, such as a low overpotential of 269 mV at 10 mA cm.
View Article and Find Full Text PDFChemphyschem
January 2025
University of North Carolina, Research Computing Center, 211 Manning Drive, 27599-3420, Chapel Hill, UNITED STATES OF AMERICA.
Covalent bonding and noncovalent interactions are important chemical concepts and how to identify them has been of current interest in the literature. Within the framework of density functional theory (DFT), we recently proposed a few qualitative descriptors to categorize different types of interactions with Pauli energy and its derivatives. In this work, we expand the scope by including the quantities derived from energetic information, which were recently proposed and thoroughly investigated by us from the framework of information-theoretic approach (ITA) in DFT.
View Article and Find Full Text PDFChemistry
January 2025
Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Muegyetem rkp 3, 1111, Budapest, HUNGARY.
New hybrids were synthesised by linking carboranes and siloles, both of which are known as aggregation-induced emission active units. Although most of the newly synthesised systems do not display notable quantum yield either in solution or in the aggregated state, they emit strongly in the solid-state, and a quantum yield of up to 100% can be achieved. The tailorable quantum yield can be attributed to the packing of the molecules in the crystal lattice ruled by the carborane and phenyl moieties according to the SC-XRD data.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!