Water Structuring Induces Nonuniversal Hydration Repulsion between Polar Surfaces: Quantitative Comparison between Molecular Simulations, Theory, and Experiments.

Polar surfaces in water typically repel each other at close separations, even if they are charge-neutral. This so-called hydration repulsion balances the van der Waals attraction and gives rise to a stable nanometric water layer between the polar surfaces. The resulting hydration water layer is crucial for the properties of concentrated suspensions of lipid membranes and hydrophilic particles in biology and technology, but its origin is unclear. It has been suggested that surface-induced molecular water structuring is responsible for the hydration repulsion, but a quantitative proof of this water-structuring hypothesis is missing. To gain an understanding of the mechanism causing hydration repulsion, we perform molecular simulations of different planar polar surfaces in water. Our simulated hydration forces between phospholipid bilayers agree perfectly with experiments, validating the simulation model and methods. For the comparison with theory, it is important to split the simulated total surface interaction force into a direct contribution from surface-surface molecular interactions and an indirect water-mediated contribution. We find the indirect hydration force and the structural water-ordering profiles from the simulations to be in perfect agreement with the predictions from theoretical models that account for the surface-induced water ordering, which strongly supports the water-structuring hypothesis for the hydration force. However, the comparison between the simulations for polar surfaces with different headgroup architectures reveals significantly different decay lengths of the indirect water-mediated hydration-force, which for laterally homogeneous water structuring would imply different bulk-water properties. We conclude that laterally inhomogeneous water ordering, induced by laterally inhomogeneous surface structures, shapes the hydration repulsion between polar surfaces in a decisive manner. Thus, the indirect water-mediated part of the hydration repulsion is caused by surface-induced water structuring but is surface-specific and thus nonuniversal.

An Entropy-Based Car Failure Detection Method Based on Data Acquisition Pipeline.

Modern cars are equipped with plenty of electronic devices called Electronic Control Units (ECU). ECUs collect diagnostic data from a car's components such as the engine, brakes etc. These data are then processed, and the appropriate information is communicated to the driver. From the point of view of safety of the driver and the passengers, the information about the car faults is vital. Regardless of the development of on-board computers, only a small amount of information is passed on to the driver. With the data mining approach, it is possible to obtain much more information from the data than it is provided by standard car equipment. This paper describes the environment built by the authors for data collection from ECUs. The collected data have been processed using parameterized entropies and data mining algorithms. Finally, we built a classifier able to detect a malfunctioning thermostat even if the car equipment does not indicate it.

Impaired control and gaming-related harm in relation to gaming Disorder.

The concept of impaired control (IC) over gaming is an important element of assessment and interventions for problem gaming and gaming-related harm. Past studies have reported that gaming disorder (GD) is associated with various negative consequences, but there is limited research on the relationship between IC over gaming and negative outcomes. To address this gap, the study investigated the relationship between impaired control and gaming-related harm among individuals with self-identified gaming disorder. It was hypothesized that IC would be positively associated with gaming-related harm and harm severity. In addition, it was predicted that IC would be a significant predictor of harm when controlling for age, gender, psychological distress, and gaming urges. The current study recruited 513 participants through an online survey platform. The Impaired Control Over Gaming Scale (ICOGS) was used to measure IC, and modified items from Browne et al.'s taxonomy of gambling harms were used to assess gaming harm severity. The logistic regression results showed that IC was positively related to all forms of harm, after controlling for other variables. The predictive value of IC was similar across financial, psychological, relationship, social and work/school domains. These results supported the importance of IC as a mechanism that contributes to the experience of gaming-related harm, and the need to target IC in interventions for GD.

Multiparticle collision dynamics simulations of viscoelastic fluids: shear-thinning Gaussian dumbbells.

The structural, dynamical, and rheological properties are studied of a multiparticle collision dynamics (MPC) fluid composed of shear-thinning Gaussian dumbbells. MPC is a mesoscale hydrodynamic simulation technique, which has successfully been applied in simulations of a broad range of complex fluids with Newtonian solvent. The MPC particles are replaced by Gaussian dumbbells, where we enforce a constant mean square length even under nonequilibrium conditions, which leads to shear thinning. This conserves the simplicity and efficiency of the original MPC fluid dynamics, since the analytical solution is known of Newton's equations of motion of the Gaussian dumbbells. Moreover, analytically obtained nonequilibrium structural, dynamical, and rheological properties are presented of Gaussian dumbbells under shear flow within the preaveraging approximation of hydrodynamic interactions. The comparison of the analytical and simulation results shows good agreement, with small deviations only due to the preaveraging approximation. In particular, we observe shear thinning and a nonzero second normal stress coefficient.

Impaired control over gaming scale (ICOGS): Development, confirmatory factor validation, and psychometric evaluation.

Background and aims: The concept of impaired control is central to addictive disorders, including gaming disorder in the DSM-5 and ICD-11. Impaired control refers to the recurrent inability to resist impulses to engage in certain activities or behaviours and the failure to limit or stop this engagement. Although numerous screening tools for gaming disorder symptoms have been developed, these instruments have limited capacity for measuring the nature and extent of impaired control. To address this limitation, the present study reports on the creation of the Impaired Control Over Gaming Scale (ICOGS), an 8-item screening tool to assess gaming-related impaired control. Methods: A total of 513 gamers, including 125 gamers (24.3%) who met the DSM-5 criteria for gaming disorder, were recruited from Prolific, an online crowd-sourcing platform. Results: The ICOGS demonstrated promising psychometric properties. Exploratory and confirmatory factor analysis using two samples provided robust support for a 2-factor model and high internal consistency of the scale. ICOGS scores were significantly and positively associated with gaming disorder symptoms, gaming-related harms, gaming frequency, psychological distress, and neuroticism. Using receiver operating characteristic analysis, the ICOGS differentiated between non-problem gamers and those who met the criteria for GD. Discussion and conclusions: Overall, the ICOGS appears to be a valid and reliable scale for use in studies of problem gaming, and may be useful for assessing outcomes of GD interventions that employ self-regulation and stopping techniques to reduce or eliminate problem gaming behavior.

Memory-kernel extraction for different molecular solutes in solvents of varying viscosity in confinement.

The friction coefficient of molecular solutes depends on the solute, on the solvent, and on the solute-solvent interactions, but is typically assumed to not depend on an externally applied force that acts on the solute. In this paper we compute the friction memory function from molecular dynamics simulations and show that the friction coefficients of harmonically confined methane, water, Na^{+}, an artificial Na^{-} ion, and glycerol in water in fact increase with confinement strength. The results show that the friction increase with confinement strength is a fundamental effect that occurs for hydrophobic, hydrophilic, as well as charged molecules. We demonstrate that a parameter-free extraction of the running integral over the memory function yields the most robust results when compared to methods based on parametrization or Fourier transforms. In all systems, this friction increase is accompanied by a slowdown of the solvent dynamics in the first hydration shell of the solutes. By simulations of a confined glycerol molecule in water-glycerol mixtures, we furthermore demonstrate that the friction dependence on the confining potential is magnified in more viscous solvents, which suggests that this effect plays an important role for larger molecules in highly viscous solutions like polymer melts, in line with dynamic scaling arguments.

Hydration Repulsion Difference between Ordered and Disordered Membranes Due to Cancellation of Membrane-Membrane and Water-Mediated Interactions.

Hydration repulsion acts between all sufficiently polar surfaces in water at small separations and prevents dry adhesion up to kilobar pressures. Yet it remained unclear whether this ubiquitous force depends on surface structure or is a sole water property. We demonstrate that previous deviations among different experimental measurements of hydration pressures in phospholipid bilayer stacks disappear when plotting data consistently as a function of repeat distance or membrane surface distance. The resulting pressure versus distance curves agree quantitatively with our atomistic simulation results and exhibit different decay lengths in the ordered gel and the disordered fluid states. This suggests that hydration forces are not caused by water ordering effects alone. Splitting the simulated total pressure into membrane-membrane and water-mediated parts shows that these contributions are opposite in sign and of similar magnitude, thus they are equally important. The resulting net hydration pressure between membranes is what remains from the near-cancellation of these ambivalent contributions.

Combination of MD Simulations with Two-State Kinetic Rate Modeling Elucidates the Chain Melting Transition of Phospholipid Bilayers for Different Hydration Levels.

The phase behavior of membrane lipids plays an important role in the formation of functional domains in biological membranes and crucially affects molecular transport through lipid layers, for instance, in the skin. We investigate the thermotropic chain melting transition from the ordered Lß phase to the disordered Lα phase in membranes composed of dipalmitoylphosphatidylcholine (DPPC) by atomistic molecular dynamics simulations in which the membranes are subject to variable heating rates. We find that the transition is initiated by a localized nucleus and followed by the propagation of the phase boundary. A two-state kinetic rate model allows characterizing the transition state in terms of thermodynamic quantities such as transition state enthalpy and entropy. The extrapolated equilibrium melting temperature increases with reduced membrane hydration and thus in tendency reproduces the experimentally observed dependence on dehydrating osmotic stress.