Lattice Dynamical Study and Elastic Property of Europium Telluride (Eute) Crystal

In the present work authors are reporting complete lattice dynamical properties of Europium telluride (EuTe). The present model works on three body rigid ion model & three body rigid shell model (TRIM & TRSM). The short-range overlap repulsion is operative up to the second neighboring ions. An excellent agreement has been obtained between theory and experiment for their all-phonon properties of (EuTe) like phonon dispersion curves, Debye temperature variations, two-phonon IR/Raman spectra, third-fourth order lattice constant, pressure derivative and anharmonic elastic properties.

Dark bubbles and black holes

In this paper we study shells of matter and black holes on the expanding bubbles realizing de Sitter space, that were proposed in [4]. We construct explicit solutions for a rigid shell of matter as well as black hole like solutions. The latter of these can also be used to construct Randall-Sundrum braneworld black holes in four dimensions.

Pericardiectomy for constrictive pericarditis

Chronic constrictive pericarditis results from inflammation and fibrosis of the pericardium. This situation eventually leads to impairment of diastolic filling and right heart failure. Once the diagnosis is made, because the disease is basically irreversible, a pericardiectomy is the mandatory treatment. The standard surgical treatment has been extensively described. The goal of this video tutorial is to render a visual explanation of the described techniques and to provide tips to help make the procedure easier to perform. The standard technique is performed through a median sternotomy, preferably without cardiopulmonary bypass if feasible. The procedure includes the complete removal of the anterior pericardium from phrenic nerve to phrenic nerve and the removal of the diaphragmatic pericardium and of part of the pericardium posterior to both phrenic nerves. Before starting the actual pericardiectomy procedure, it is useful to separate the pericardial rigid shell from the pleurae and from the diaphragm; this step allows the operator to see both phrenic nerves clearly and to give clear boundaries between the pericardium and the diaphragm, which are not often as clear as desirable due to fat, edema, inflammation, and scarring. Once a portion of the pericardium has been detached from the myocardium, it can be excised, making the portion yet to be removed more visible.

Lattice Dynamical Study of Platinum by Use of van der Waals Three Body Force Shell Model

In present article author considered the lattice dynamical study of platinum by use of van der Waals three body force shell model [VTBFSM] due to high stiffness constant C11 and C12 . The present model uses with the frequencies of the optical and vibrational branches in the direction [100] and phonon density of states.The study of phonon spectra are important in determining the mechanica1, electrical and thermodynamical properties of elements and their alloys. The present model incorporates the effect of (VWI) and (TBI) into the rigid shell model with fcc structure, operative up to the second neighbors in short range interactions. The available measured data for platinum (Pt) well agrees with our results.

Mechanics unlocks the morphogenetic puzzle of interlocking bivalved shells

Brachiopods and mollusks are 2 shell-bearing phyla that diverged from a common shell-less ancestor more than 540 million years ago. Brachiopods and bivalve mollusks have also convergently evolved a bivalved shell that displays an apparently mundane, yet striking feature from a developmental point of view: When the shell is closed, the 2 valve edges meet each other in a commissure that forms a continuum with no gaps or overlaps despite the fact that each valve, secreted by 2 mantle lobes, may present antisymmetric ornamental patterns of varying regularity and size. Interlocking is maintained throughout the entirety of development, even when the shell edge exhibits significant irregularity due to injury or other environmental influences, which suggests a dynamic physical process of pattern formation that cannot be genetically specified. Here, we derive a mathematical framework, based on the physics of shell growth, to explain how this interlocking pattern is created and regulated by mechanical instabilities. By close consideration of the geometry and mechanics of 2 lobes of the mantle, constrained both by the rigid shell that they secrete and by each other, we uncover the mechanistic basis for the interlocking pattern. Our modeling framework recovers and explains a large diversity of shell forms and highlights how parametric variations in the growth process result in morphological variation. Beyond the basic interlocking mechanism, we also consider the intricate and striking multiscale-patterned edge in certain brachiopods. We show that this pattern can be explained as a secondary instability that matches morphological trends and data.

MECHANICAL FEEDBACK IN SEASHELL GROWTH AND FORM

Mollusc seashells grow through the local deposition and calcification of material at the shell opening by a soft and thin organ called the mantle. Through this process, a huge variety of shell structures are formed. Previous models have shown that these structural patterns can largely be understood by examining the mechanical interaction between the deformable mantle and the rigid shell aperture to which it adheres. In this paper we extend this modelling framework in two distinct directions. For one, we incorporate a mechanical feedback in the growth of the mollusc. Second, we develop an initial framework to couple the two primary and orthogonal modes of pattern formation in shells, which are termed antimarginal and commarginal ornamentation. In both cases we examine the change in shell morphology that occurs due to the different mechanical influences and evaluate the hypotheses in light of the fossil record.