An investigation and modelling of energy dissipation through sloshing in an egg-shaped shell

Sloshing absorbers work on a similar principle to that of tuned vibration absorbers. A sloshing absorber consists of a tank, partially filled with liquid. The absorber is attached to the structure to be controlled, and relies on the structure's motion to excite the liquid. Consequently, a sloshing wave is produced at the liquid free surface possessing energy dissipative qualities to suppress excessive vibrations of the structure.The hen's egg has evolved to dissipate vibration energy rapidly to protect its contents. An uncooked hen's egg's capability to rapidly dissipate potentially harmful energy, is due to sloshing of its contents. Hence, there may be lessons to learn from the natural design of an egg which could be employed in the engineered (artificial) design of a sloshing absorber.The primary objective of this work is to identify the physical events responsible for effective energy dissipation in an eggshell, at different fill levels. A secondary objective is to demonstrate the suitability of the Smoothed Particle Hydrodynamics (SPH) method for numerical predictions in such an unusually shaped shell. Through numerical predictions, the possibility of modifying the egg's design to further encourage dissipation patterns is explored briefly. Simple experiments are also presented to check the validity of the numerical predictions.     

A theoretical approach to the formation mechanism of diphenyldithieno[3,2-b:2′,3′-d]thiophene from 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene: a DFT study

The mechanism of formation of dithieno[3,2-b:2′,3′-d]thiophene (DTT) through the reaction of 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene with P₄S₁₀ was examined in detail by employing DFT method at B3LYP/6-311+G(d,p) level. Two mechanisms were considered. The first one included two parts (i) transformation of the 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene to the dithione by the reaction of P₄S₁₀ with the carbonyl groups and (ii) cyclization of the dithione to the final product, DTT, through an intramolecular reaction of the thiophene with thiones. The second mechanism consists of an initial attack of the carbonyl oxygen to the phosphorus atom of P₄S₁₀ followed by cyclization via an intramolecular attack from the thiophene ring to the highly electrophilic carbons connected to the oxygens to form DTT. According to the calculated Gibbs free energies of the studied paths, the second mechanism is more favorable than the first one and both pathways proceed in a stepwise manner.     

Highly selective fluoride sensing via chromogenic aggregation of a silyloxy-functionalized tetraphenylethylene (TPE) derivative

A silyloxy-functionalized tetraphenylethylene (TPE) derivative shows a remarkable change in the absorption spectrum on deprotection with fluoride ions. The reaction process is highly selective for fluoride and the resulting charge transfer band results in a bright green solution. A simple selective visual assay of aqueous fluoride ions was also obtained by the impregnation of cellulose strips with the TPE derivative.     

Some metal chelates with Schiff base ligand: synthesis,structure elucidation,thermal behavior,XRD evaluation,antioxidant activity,enzyme inhibition,and molecular docking studies

Molecular Diversity - Schiff bases are well-known compounds for having significant biological properties. In this study, a new Schiff base ligand and its metal complexes were synthesized, and their...     

Spectroscopic ellipsometry study of above-band gap optical constants of layered structured TlGaSe2, TlGaS2 and TlInS2 single crystals

Spectroscopic ellipsometry measurements on TlGaSe₂, TlGaS₂ and TlInS₂ layered crystals were carried out on the layer-plane (0 0 1) surfaces, which are perpendicular to the optic axis c^?, in the 1.2–6.2 eV spectral range at room temperature. The real and imaginary parts of the pseudodielectric function as well as pseudorefractive index and pseudoextinction coefficient were found as a result of analysis of ellipsometric data. The structures of critical points in the above-band gap energy range have been characterized from the second derivative spectra of the pseudodielectric function. The analysis revealed four, five and three interband transition structures with critical point energies 2.75, 3.13, 3.72 and 4.45 eV (TlGaSe₂), 3.03, 3.24, 3.53, 4.20 and 4.83 eV (TlGaS₂), and 3.50, 3.85 and 4.50 eV (TlInS₂). For TlGaSe₂ crystals, the determined critical point energies were assigned tentatively to interband transitions using the available electronic energy band structure.     

5,6‐Di­phenyl­[1,3]­di­thiolo­[4,5‐b]di­thiine‐2‐thione

In the title compound, C₁₇H₁₀S₅, the dithiine ring adopts a boat conformation while the di­thiole ring has an envelope conformation. The phenyl groups are planar and make dihedral angles of 40.7 (2) and 59.8 (2)° with the best plane of the thiine ring. The shortest intermolecular S?S contact is 3.305 (2) Å.     

Modeling the dynamics of interest rate volatility with skewed fat-tailed distributions

This paper proposes generalized parametric models of the short-term interest rate that nest one-factor CEV and discrete time GARCH models. The paper estimates the generalized and nested models with skewed fat-tailed distributions to determine the correct specification of the conditional distribution of interest rates. The results indicate that the discrete time models that incorporate the level and GARCH effects into the diffusion function and that accommodate the tail-thickness of the interest rate distribution perform much better than the CEV model in forecasting the future volatility of interest rates. The results also show that the significance of nonlinearity in the drift function relies crucially on the specification of the volatility function.     

Analysis of confocal microscopy image data of Physcomitrella chloroplasts to reveal adaptation principles leading to structural stability at the nanoscale

Proteins of the FtsZ (filamentous temperature-sensitive Z) family establish complex polymeric spatial patterns in plastids of the moss Physcomitrella patens. These structures represent a "plastoskeleton" that might contribute to plastid shape and stability. The aim of this work is to develop computer models of FtsZ network connectivity and dynamics. These computer models are developed from green fluorescent protein (GFP) images obtained by Prof. Reski's Plant Biotechnology group at the University of Freiburg by means of laser scanning confocal microscopy. Subsequently, structural reconstruction techniques based on cellular automata algorithm are applied on the raw image data to compensate for any information that is lost in the process of imaging. Segmentation of the processed data will result in the computer model of the targeted structures, which are used for further analysis. Model generation and experimental testing in the moss system is conducted in an iterative process with the aim of both forward and reverse biomimetics. A developed image processing algorithm with the aim of quantification of structural characteristics is utilized to extract structural features of the FtsZ network in Physcomitrella enabling us a statistical analysis on the extracted data. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)