Intermolecular vibrations and volumetric properties are investigated using the quasiharmonic approximation with the TIP4P/2005, TIP4P/Ice, and SPC/E potential models for most of the known crystalline and amorphous ice forms that have hydrogen-disordering. The ice forms examined here cover low pressure ices (hexagonal and cubic ice I, XVI, and hypothetical dtc ice), medium pressure ices (III, IV, V, VI, XII, hydrogen-disordered variant of ice II), and high pressure ice (VII) as well as the low density and the high density amorphous forms. We focus on the thermal expansivities and the isothermal compressibilities in the low temperature regime over a wide range of pressures calculated via the intermolecular vibrational free energies. Negative thermal expansivity appears only in the low pressure ice forms. The sign of the thermal expansivity is elucidated in terms of the mode Grüneisen parameters of the low frequency intermolecular vibrational motions. Although the band structure for the low frequency region of the vibrational density of state in the medium pressure ice has a close resemblance to that in the low pressure ice, its response against volume variation is opposite. We reveal that the mixing of translational and rotational motions in the low frequency modes plays a crucial role in the appearance of the negative thermal expansivity in the low pressure ice forms. The medium pressure ices can be further divided into two groups in terms of the hydrogen-bond network flexibility, which is manifested in the properties on the molecular rearrangement against volume variation, notably the isothermal compressibility.
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Sci Rep
January 2025
Department of Astronomy, Astrophysics and Space Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, 453552, India.
Arctic precipitation plays a crucial role in shaping the surface mass balance of Arctic sea ice and has wide-ranging impacts on local climate, ecosystems, and global sea level dynamics. With the Arctic undergoing warming trends, historical data and climate models indicate a shift from primarily snowfall to a rise in liquid and mixed forms of precipitation. This study tried to explain the microphysical characteristics and atmospheric conditions associated with different forms of precipitation and their transitions.
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January 2025
Department of Geology, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland.
Massive injection of C depleted carbon to the ocean and atmosphere coincided with major environmental upheaval multiple times in the geological record. For several events, the source of carbon has been attributed to explosive venting of gas produced when magmatic sills intruded organic-rich sediment. The concept mostly derives from studies of a few ancient sedimentary basins with numerous hydrothermal vent complexes (HTVCs) where craters appear to have formed across large areas of the seafloor at the same time, but good examples remain rare in strata younger than the Early Eocene.
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January 2025
School of Geographic Science, Changchun Normal University, Changchun, 130102, China.
Climate change and human activities affect the biomass of different algal and the succession of dominant species. In the past, phytoplankton phyla inversion has been focused on oceanic and continental shelf waters, while phytoplankton phyla inversion in inland lakes and reservoirs is still in the initial and exploratory stage, and the research results are relatively few. Especially for mid-to-high latitude lakes, the research is even more blank.
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January 2025
Faculty of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi ave. 71/23, 050040 Almaty, Kazakhstan.
This study investigates the formation of carbon dioxide clathrate hydrates under conditions simulating interstellar environments, a process of significant astrophysical and industrial relevance. Clathrate hydrates, where gas molecules are trapped within water ice cages, play an essential role in both carbon sequestration strategies and understanding of the behavior of ices in space. We employed a combination of Fourier Transform Infrared (FTIR) spectroscopy, mass spectrometry, temperature-programmed desorption (TPD), and Density Functional Theory (DFT) calculations to explore thin films of HO:CO ice mixtures with varying CO concentrations (5-75%) prepared by vapor deposition at temperatures ranging between 11 and 180 K.
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January 2025
Cardiovascular Research Institute, General Hospital of Northern Theater Command, No. 83 Wenhua Road, Shenhe District, Shenyang, 110016, Liaoning, China.
Using transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) to investigate the occurrence and related causes of iatrogenic atrial septal defect (iASD) after catheter ablation combined with left atrial appendage closure (LAAC) for atrial fibrillation (AF) and its impact on the right heart system. We retrospectively analyzed 330 patients that underwent combined procedure of catheter ablation for AF and LAAC at General Hospital of Northern Theater Command from January 2018 to March 2022. These patients were divided into iASD group and non-iASD group according to whether there was persistent iASD shown on TEE at 3 months after procedure.
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