Dynamic disorder, Strain and Sublimation of Crystalline Caged Hydrocarbons from First Principles

Caged hydrocarbons exhibit diverse molecular and material properties thanks to a large variability of the three-dimensional carbon backbone of such molecules. High molecular symmetry of caged hydrocarbons predetermines these materials to pack very efficiently in crystal lattices that belong to highly symmetric space groups, as well as to easily form plastic solid phases with highly pronounced dynamic disorder in the vicinity of the melting temperature. This work aims at resolving the literature debate about the two contradictory values of experimental sublimation enthalpy for cubane, being a typical state of the art for such uncommon molecules. For this purpose, we use density functional theory (DFT) powered quasi-harmonic protocol, further fortified with the ab inito fragment-based calculation of the cohesive energy of crystalline cubane at the CCSD(T) level. Further, this work presents a viable first-principles treatment of dynamic disorder of molecules via their hindered rotations in the crystal lattice. A protocol for assessment of the energetic and entropic aspects of this local disorder, as well as to the related anharmonic contributions to the thermodynamic properties arising from these dynamic degrees of freedom is presented and validated. Finally, the question, whether the molecular steric strain is compensated by stronger crystal cohesion, is addressed

Age -Related Variations in Takotsubo Syndrome

© 2020 by the American College of Cardiology Foundation.BACKGROUND: Takotsubo syndrome (TTS) occurs predominantly in post-menopausal women but is also found in younger patients. OBJECTIVES: This study aimed to investigate age-related differences in TTS. METHODS: Patients diagnosed with TTS and enrolled in the International Takotsubo Registry between January 2011 and February 2017 were included in this analysis and were stratified by age (younger: #50 years, middle-age: 51 to 74 years, elderly: $75 years). Baseline characteristics, hospital course, as well as short- and long-term mortality were compared among groups. RESULTS Of 2,098 TTS patients, 242 (11.5$75 years of age. Younger patients were more often men (12.4% vs. 10.9% vs. 6.3%; p ¼ 0.002) and had an increased prevalence of acute neurological (16.3% vs. 8.4% vs. 8.8%; p ¼ 0.001) or psychiatric disorders (14.1% vs. 10.3% vs. 5.6%; p < 0.001) compared with middle-aged and elderly TTS patients. Furthermore, younger patients had more often cardiogenic shock (15.3% vs. 9.1% vs. 8.1%; p ¼ 0.004) and had a numerically higher in-hospital mortality (6.6% vs. 3.6% vs. 5.1%; p ¼ 0.07). At multivariable analysis, younger (odds ratio: 1.60; 95% confidence interval: 0.86 to 3.01; p ¼ 0.14) and older age (odds ratio: 1.09; 95% confidence interval: 0.66 to 1.80; p ¼ 0.75) were not independently associated with in-hospital mortality using the middle-aged group as a reference. There were no differences in 60-day mortality rates among groups. CONCLUSIONS: A substantial proportion of TTS patients are younger than 50 years of age. TTS is associated with severe complications requiring intensive care, particularly in younger patients.info:eu-repo/semantics/publishedVersio