Effect of Initial Conditions and Numerical Investigation of Instability Developed during Synthesis of TiC via Vortex Combustion at Moderate Temperatures. Model of Vortex Combustion

Despite the fact that the classical theory of combustion (CTC) operates with the simplest, elementary objects and concepts, such as: flat or slightly curved combustion fronts, elementary combustion models and potential flows. there are some problems that the CTC is only facing with a sufficiently strong curvature of the front. For example, Markstein's solution in the problem of hydrodynamic instability of a plane combustion front. In the work presented by the authors, the problem of stabilizing the titanium carbide synthesis front at moderate temperatures, which cannot be plane due to the thermo physical features of the system under consideration (Le<<1, Ze=6.03 at Тad=3300К), is similarly solved. A model of vortex combustion with a spirally curved front is proposed, the numerical analysis of which showed the stability of similar front of the TiC synthesis in the field of vortex hydrodynamic currents. The resulting solution can serve as a complete alternative to the mode of spiral spin combustion (or rather, to its branch with a low orbital speed and a low combustion temperature) of such systems, not only considered conditionally unstable in CTC, but also actually manifesting this instability during numerical calculations of the area of the existence of a spinal spot with a small radius and great curvature.

How does curvature affect the free-energy barrier of stalk formation? Small vesicles vs apposing, planar membranes

Using molecular simulations of POPC lipids in conjunction with the calculation of the Minimum Free-Energy Path (MFEP), we study the effect of strong membrane curvature on the formation of the first fusion intermediate—the stalk between a vesicle and its periodic image. We find that the thermodynamic stability of this hourglass-shaped, hydrophobic connection between two vesicles is largely increased by the strong curvature of small vesicles, whereas the intrinsic barrier to form a stalk, i.e., associated with dimple formation and lipid tails protrusions, is similar to the case of two, apposing, planar membranes. A significant reduction of the barrier of stalk formation, however, stems from the lower dehydration free energy that is required to bring highly curved vesicle into a distance, at which stalk formation may occur, compared to the case of apposing, planar membranes.

Schwarzschild black hole states and entropies on a nice slice

In this work, we define a quantum gravity state on a nice slice. The nice slices provide a foliation of spacetime and avoid regions of strong curvature. We explore the topology and the geometry of the manifold obtained from a nice slice after evolving it in complex time. We compute its associated semiclassical thermodynamics entropy for a 4d Schwarzschild black hole. Despite the state one can define on a nice slice is not a global pure state, remarkably, we get a similar result to Hawking’s calculation. In the end, we discuss the entanglement entropy of two segments on a nice slice and comment on the relation of this work with the replica wormhole calculation.

Cooperatively rearranging regions change shape near the mode-coupling crossover for colloidal liquids on a sphere

The structure and dynamics of liquids on curved surfaces are often studied through the lens of frustration-based approaches to the glass transition. Competing glass transition theories, however, remain largely untested on such surfaces and moreover, studies hitherto have been entirely theoretical/numerical. Here we carry out single particle-resolved imaging of dynamics of bi-disperse colloidal liquids confined to the surface of a sphere. We find that mode-coupling theory well captures the slowing down of dynamics in the moderate to deeply supercooled regime. Strikingly, the morphology of cooperatively rearranging regions changed from string-like to compact near the mode-coupling crossover—a prediction unique to the random first-order theory of glasses. Further, we find that in the limit of strong curvature, Mermin–Wagner long-wavelength fluctuations are irrelevant and liquids on a sphere behave like three-dimensional liquids. A comparative evaluation of competing mechanisms is thus an essential step towards uncovering the true nature of the glass transition.

Visualization of stent apposition after stent-assisted coiling of intracranial aneurysms using high resolution 3D fusion images acquired by C-arm CT

PurposeWe used an imaging technique based on 3-dimensional (3D) C-arm CT to assess the apposition of three types of stents after coiling of intracranial aneurysms.MethodsAll patients with intracranial aneurysms were considered who received stent-assisted coiling with Enterprise2, Neuroform EZ, or Neuroform Atlas stents confirmed by C-arm CT imaging at our institution between June 2015 and November 2017. A 3D digital subtraction angiography (DSA) scan for vessel imaging followed by a high-resolution cone beam CT (HR-CBCT) scan for coil and stent imaging was performed. The images were fused to obtain dual volume 3D fusion images. We investigated malapposition of the stent trunk (crescent sign) and of the stent edges (edge malapposition) and used the χ2 statistic to test for an association with stent types. Inter-rater agreement between two raters was estimated using Cohen’s kappa statistics.ResultsWe evaluated 75 consecutive cases. Enterprise2 stents were used in 22 cases, Neuroform EZ in 26, and Neuroform Atlas in 27 cases. By stent type, crescent sign was detected in 27% of Enterprise2, 8% of Neuroform EZ, and none of Neuroform Atlas stents (p=0.007), while edge malapposition was detected in 27% of Enterprise2, 58% of Neuroform EZ, and 30% of Neuroform Atlas stents (p=0.05). Excellent (κ=0.81) and good (κ=0.78) agreement between the raters was found for the detection of edge apposition and crescent sign, respectively.ConclusionStent malapposition was clearly visualized by dual volume 3D imaging. The Neuroform Atlas stents showed good apposition even in vessels with strong curvature.

Alteration of cardiolipin-dependent mitochondrial coupling in muscle protects against obesity

SummaryThe tubular shape of mitochondrial cristae depends upon a specific composition of the inner mitochondrial membrane, including cardiolipin that allows strong curvature and promotes optimal organization of ATP synthase. Here we identify Hacd1, which encodes an enzyme involved in very long chain fatty acid biosynthesis, as a key regulator of composition, structure and functional properties of mitochondrial membranes in muscle. In Hacd1-deficient mice, the reduced cardiolipin content was associated with dilation of cristae and caused defective phosphorylating respiration, characterized by absence of proton leak and oxidative stress.The skeletal muscle-specific mitochondrial coupling defect produced a global elevation in basal energy expenditure with increased carbohydrate and lipid catabolism, despite decreased muscle mass and locomotor capacities. Mice were protected against diet-induced obesity despite reduced muscle activity, providing an in vivo proof of concept that reducing mitochondrial coupling efficiency in skeletal muscle might be an actionable mechanism in metabolic disease conditions.