Instituto de Química, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos 149, CT, Bl. A-622, Cid. Univ., Rio de Janeiro, RJ, 21941-909, Brazil.
Published: October 2020
AI Article Synopsis
Article Abstract
Alkanes are a fundamental part in empirical force fields (FF) not only due to their technological relevance, but also due to the prevalence of alkane moieties in organic molecules, e.g., compounds containing a saturated carbon chain. Therefore, a good description of alkane interactions is crucial for determining the quality of a FF. In this study, the performance of 12 empirical force fields (FF) was evaluated in the context of reproducing liquid properties of alkanes. More specifically, n-octane was chosen as a reference compound since it is a liquid in a broad temperature range and it has numerous experimental data for thermodynamic, transport, and structural properties, as well as for their temperature dependencies. A normalized root-mean-square deviation (NRMSD) analysis was used to rank the force fields in their ability to reproduce the experimental data. Five out of the six best force fields considered were united-atom models. The GROMOS force field showed the smallest deviation in terms of NRMSD, followed by TRAPPE-EH, NERD, CHARMM-UA, TRAPPE-UA, and OPLS-UA. This overall better performance of the united-atom force fields indicates that complexity does not always bring quality.
The amber-OL21 force field (ff) was developed to better describe noncanonical DNA, including Z-DNA. Despite its improvements for DNA simulations, this study found that OL21's scope of application was limited by embedded ff artifacts. In a benchmark set of seven DNA molecules, including two double-stranded DNAs transitioning between B- and Z-DNA and five single-stranded DNAs folding into mini-dumbbell or G-quadruplex structures, the free energy landscapes obtained using OL21 revealed several issues: Z-DNA was overly stabilized; misfolded states in mini-dumbbell DNAs were most stable; DNA GQ folding was consistently biased toward an antiparallel topology.
Traumatic brain injury (TBI) after high-energy, behind helmet blunt trauma (BHBT) is an important but poorly understood clinical entity often associated with apnea and death in humans. In this study, we use a swine model of high-energy BHBT to characterize key neuropathologies and their association with acute respiratory decompensation. Animals with either stable or critical vital signs were euthanized within 4 h after injury for neuropathological assessment, with emphasis on axonal and vascular pathologies in the brainstem.
Collaborative organising is known to burn like a rocket: it thrives on intense passion, relationality and creativity but quickly falls into pieces. This article explores the underestimated role of events and their affective atmospheres to sustain collaborative work. Drawing insights from two ethnographic field studies within an open-source software community and a network of impact entrepreneurs, we introduce the notion of 'polyrhythmic affectivity' at the core of polycentric governance.
Introduction: Traumatic brain injury (TBI) is a critical global health issue characterized by perturbance in cerebral function attributed to mechanical force. TBI often precipitates significant visual impairment that negatively impacts the patients' quality of life. This review examines the effects of TBI on visual function from a neuro-ophthalmological perspective, focusing on the assessment, diagnostics, and management of associated sequelae.
Gravitational Field-Flow Fractionation (GrFFF) is an elution-based method designed for the separation of particles ranging from a few micrometers up to approximately 100 μm in diameter. Separation occurs over time, with particles being fractionated based on size and other physico-chemical properties. GrFFF takes advantage of gravitational forces acting perpendicularly to a laminar flow in a thin channel.
