The criteria for the existence of a glass transition in a planar vortex array with quenched disorder are studied. Applying a replica Bethe ansatz, we obtain for self-avoiding vortices the exact quenched average free energy and effective stiffness which is found to be in excellent agreement with recent numerical results for the related random bond dimer model [C. Zeng, P. L. Leath, and T. Hwa, Phys. Rev. Lett. 83, 4860 (1999)] Including a repulsive vortex interaction and a finite vortex persistence length xi, we find that for xi-->0 the system is at all temperatures in a glassy phase; a glass transition exists only for finite xi. Our results indicate that planar vortex arrays in superconducting films are glassy at presumably all temperatures.
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http://dx.doi.org/10.1103/PhysRevLett.90.185701 | DOI Listing |
Mol Pharm
March 2025
Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
Polyamorphism in organic molecules is a poorly understood and controversial phenomenon related to amorphous materials. Although very few studies, including our own, have demonstrated the existence of polyamorphism in drug molecules, this solid-state phenomenon is still very elusive and the investigation of its occurrence in other drugs is fundamental to understand its formation. Indomethacin (IND) has been recently discussed in the literature as a potential drug exhibiting polyamorphism.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
March 2025
Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
Low-energy excitations play a key role in all condensed-matter systems, yet there is limited understanding of their nature in glasses, where they correspond to local rearrangements of groups of particles. Here, we introduce an algorithm to systematically uncover these excitations up to the activation energy scale relevant to structural relaxation. We use it in a model system to measure the density of states on a scale never achieved before, confirming that this quantity shifts to higher energy under cooling, precisely as the activation energy does.
View Article and Find Full Text PDFJ Phys Chem B
March 2025
Department of Chemistry, University of Rome Sapienza, Rome 00185, Italy.
We present a structural characterization of a low-transition-temperature mixture (LTTM), consisting of thymol and carvacrol, at an equimolar ratio. Carvacrol and thymol are natural regioisomers of terpenes. When combined at an equimolar ratio, they form a liquid mixture at room temperature, with supercooling capability and glass transition at ca.
View Article and Find Full Text PDFBJPsych Open
March 2025
Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK.
Background: Women's authorship position in science, technology, engineering, mathematics and medicine research reflects career progression, especially the transition from first to last (usually senior) author. Employment of women in mental health sciences has increased, and so should have had an impact on the change to senior author position.
Aims: To identify if first or last women's authorship has changed, and mental health has better representation.
The instant crystallization of semi-crystalline polymers has become possible following the recent advances in Fast Scanning Calorimetry (FSC) and enables us to make a bridge between the time scale available experimentally with those accessible with computer simulations. Although the FSC observations have provided new information on the crystallization kinetics and evolution of the crystals, the molecular details on the chain exchange events between the ordered and disordered domains of crystals have remained elusive. Using molecular dynamics simulations, we examined the detailed chain dynamics and thermodynamics of polyamide 6 (PA6) system under two heating treatments: (i) quenching PA6 melt deeply below the melting temperature Tm and (ii) annealing the resulting quenched system to a temperature close to Tm.
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