We study the evolution of initial temperature profiles in a two-dimensional isolated harmonic graphene lattice. Two heat transfer problems are solved analytically and numerically. In the first problem, the evolution of a spatially sinusoidal initial temperature profile is considered. This profile is usually generated in real experiments based on the transient thermal grating technique. It is shown that at short times the amplitude of the profile decreases by an order magnitude and then it performs small decaying oscillations. A closed-form solution, describing the decay of the amplitude at short times is derived. It shows that due to symmetry of the lattice, the anisotropy of the ballistic heat transfer is negligible at short times, while at large times it is significant. In the second problem, a uniform spatial distribution of the initial temperature in a circle is specified. The profile is the simplest model of graphene heating by an ultrashort localized laser pulse. The corresponding solution has the symmetry of the lattice and many local maxima. Additionally, we show that each atom has two distinct temperatures corresponding to motions in zigzag and armchair directions. Presented results may serve for proper statement and interpretation of laboratory experiments and molecular dynamics simulations of unsteady heat transfer in graphene.
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http://dx.doi.org/10.1088/1361-648X/ac5197 | DOI Listing |
Mar Pollut Bull
January 2025
UiT The Arctic University of Norway, N-9037 Tromsø, Norway.
Fishing gears are conventionally made from non-biodegradable materials including polyamide (PA). When lost in the ocean, these gears have long-lasting impacts, including marine littering, microplastics production, leaching of chemicals, and an extended period of ghost fishing due to its durability. The use of biodegradable co-polyester material such as polybutylene succinate co-adipate-co-terephthalate (PBSAT) and polybutylene succinate-co-butylene adipate (PBSA) as fishing gear materials have been considered as a potential solution to reduce the associated impact.
View Article and Find Full Text PDFSleep Med
January 2025
Groupe Adène, Montpellier, France; Department of Respiratory Diseases, Montpellier University Hospital, Arnaud de Villeneuve Hospital, Montpellier, France; PhyMedExp (INSERM U 1046, CNRS UMR9214), Montpellier University, Montpellier, France. Electronic address:
Background: Although seasonal variations in CPAP-usage are often attributed to changes in temperature, no real-world study has evaluated the influence of temperature on long-term CPAP-usage.
Methods: The TempCPAP study is a retrospective real-life cohort study. Adult patients newly treated and undergoing at least 1 month of CPAP were included.
Acta Crystallogr B Struct Sci Cryst Eng Mater
February 2025
CSIRO Division of Mineral Products, Port Melbourne, Victoria, Australia.
The crystallographic phase change from tetragonal litharge (α-PbO; P4/nmm) to orthorhombic massicot (β-PbO; Pbcm) has been studied by full-matrix Rietveld analysis of high-temperature neutron powder diffraction data collected in equal steps from ambient temperature up to 925 K and back down to 350 K. The phase transformation takes place between 850 and 925 K, with the coexisting phases having equal abundance by weight at 885 K. The product massicot remains metastable on cooling to near ambient temperature.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Department of Physics, Indian Institute of Technology (IIT) Delhi, New Delhi 110016, India.
The concept of inert matrix fuel (IMF) has been proposed to utilize the energetic value of Pu and transmute minor actinides in nuclear reactors. In order to offset the initial reactivity of nuclear fuel, gadolinium (Gd) is employed as a burnable poison, owing to its high neutron absorption cross-section. To gain insights into the radiation stability and influence of grain boundaries on irradiation behaviour, 5 mol% Gd-doped ceria samples, sintered at varying temperatures, were subjected to irradiation using 400 Kr ions.
View Article and Find Full Text PDFHeliyon
January 2025
Risk and Vulnerability Science Centre, Faculty of Science and Agriculture, University of Fort Hare, P. Bag X1314, 1 King William's Town Road, Alice, 5700, South Africa.
This study explores the factors influencing smallholder farmers' decisions on livestock ownership and herd size in the context of climate change. A cross-sectional approach was employed, using a multi-stage sampling method to survey 600 smallholder farmers, 495 of whom were engaged in livestock production. Data were collected through a semi-structured questionnaire and analysed using a double hurdle model.
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