Synthesis and Characterization of New Light Emitter Symmetrical Phenoxazinium Salt and Its Potential Application as Sensor for Assessment of Hg2+

The sensitization of the excited triplet state of a novel symmetrical Bis(dialkylamino)phenoxazinium salt was developed in the presence of Hg²⁺. This effect was used to determine the concentration of Hg²⁺ in different water samples. The phenoxazinium salt sensor was characterized by different spectroscopic tools such as: UV, FTIR, NMR and fluorescence spectra. The sensor has an emission band at 347 nm in DMSO. Hg²⁺ in DMSO at pH 5.6 can remarkably quench the fluorescence intensity of the sensor at 347 nm and a new band was appeared at 436 nm due to the strong complex formation between Hg²⁺ and sensor. The quenching of the band intensity at 347 and the enhancement of the intensity of the new band at 436 were used to determine the Hg²⁺ in different waste water samples. The dynamic range found for the determination of Hg²⁺ concentration is 8.7?×?10^-10 – 1.4?×?10^-6 mol L^?1 with a detection limit of 5.8?×?10^?10 mol L^?1 and quantification detection limit of 1.8?×?10^-9 mol L^-1.     

Sandwich Complex‐Containing Macromolecules: Property Tunability Through Versatile Synthesis

Sandwich complexes feature unique properties as the physical and electronic properties of a hydrocarbon ligand or its derivative are integrated into the physical, electronic, magnetic, and optical properties of a metal. Incorporation of these complexes into macromolecules results in intriguing physical, electrical, and optical properties that were hitherto unknown in organic‐based macromolecules. These properties are tunable through well‐designed synthetic strategies. This review surveys many of the synthetic approaches that have resulted in tuning the properties of sandwich complex‐containing macromolecules. While the past two decades have seen an ever‐growing number of research publications in this field, gaps remain to be filled. Thus, we expect this review to stimulate research interest towards bridging these gaps, which include the insolubility of some of these macromolecules as well as expanding the scope of the sandwich complexes.

     

Quantum Discord in Optical Coherent States

We study the dynamics of quantum correlation of optical coherent-state qubits affected by the environment. It consists in sending these states via a decohering quantum channel. The states used as the support of the encoding information are affected by an amplitude damping channel. The quantum discord is one of type of quantum correlations between the qubits. The discord and its dynamics of two qubits in non-Markovian environments are evaluated.     

Theoretical characterisation of highly efficient dye-sensitised solar cells

Molecular electronic structure calculations, employing density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methodologies, have been carried out to improve the performance of the synthesised dye YD2-o-C8 which is characterised by 11.9%–12.7% efficiencies. We aimed to narrow the band gap of YD2-o-C8 to extend the light-harvesting region to near-infrared (NIR). This was done by incorporating Cd instead of Zn onto the porphyrin ring and elongating the length of π-conjugation by adding ethynylene link and anthracene unit, so that the performances of the suggested cells could be expected to exceed the 11.9%–12.7% efficiencies with TiO₂, ZnO₂, and WO₃ oxide electrodes. The effects of modifying the central metal and elongating the length of π-conjugation on cell performance are confirmed in terms of frontier molecular orbital (FMO) energy gaps, density of states (DOS), molecular electrostatic potentials (MEPs), non-linear optical (NLO) properties, ultraviolet–visible (UV–vis) electronic absorption, and ¹H nuclear magnetic resonance chemical shifts. Increasing the length of π-conjugation of the D–π–A dyes leads to increasing the DOS near Fermi levels, more active NLO performance, strong response to the external electric field, delocalisation of the negative charges near the anchoring groups, deep electron injection, suppressing macrocycle aggregation, active dye regeneration, and inhibited dye recombination. The calculated band gap/eV of the present DMP-Zn is correlated with the experimental (E_1/2(oxidation)–E_1/2(reduction)/V) potentials of the identical YD2-o-C8. A co-sensitiser is suggested for NIR sensitisation (550–950 nm) to increase the power-to-conversion efficiency beyond 14%.     

Effects of Anisotropy and Drying Air Parameters on Drying of Deformable Porous Media Hydro-Dynamically and Thermally Anisotropic

The purpose of this work was to investigate numerically the drying of saturated deformable porous media. The considered sample is a rectangular porous plate which assumed to be both hydro-dynamically and thermally anisotropic, while the mechanical behavior of the sample is supposed to be isotropic. All walls of the plate are subjected to a convective heat flux. Moreover, the top and bottom walls are allowed the mass transfer. The Darcy–Brinkman extended model was used as the momentum balance equation for the liquid and solid phases. The energy balance equation is based on the local thermodynamic equilibrium assumption between the both phases. The lattice Boltzmann method is used to solve the governing differential equation system. A comprehensive analysis of the effect of anisotropy and the drying air parameters on macroscopic fields is investigated throughout this work.     

Finite elastic deformations of transversely isotropic circular cylindrical tubes

We consider the finite radially symmetric deformation of a circular cylindrical tube of a homogeneous transversely isotropic elastic material subject to axial stretch, radial deformation and torsion, supported by axial load, internal pressure and end moment. Two different directions of transverse isotropy are considered: the radial direction and an arbitrary direction in planes normal locally to the radial direction, the only directions for which the considered deformation is admissible in general. In the absence of body forces, formulas are obtained for the internal pressure, and the resultant axial load and torsional moment on the ends of the tube in respect of a general strain-energy function. For a specific material model of transversely isotropic elasticity, and material and geometrical parameters, numerical results are used to illustrate the dependence of the pressure, (reduced) axial load and moment on the radial stretch and a measure of the torsional deformation for a fixed value of the axial stretch.     

Atomic to Continuum Passage for Nanotubes: A Discrete Saint-Venant Principle and Error Estimates

We consider general infinite nanotubes of atoms in ${\mathbb{R}^3}$ where each atom interacts with all the others through a two-body potential. At the equilibrium, the positions of the atoms satisfy a Euler–Lagrange equation. When there are no exterior forces and for a suitable geometry, a particular family of nanotubes is the set of perfect nanotubes at the equilibrium. When exterior forces are applied on the nanotube, we compare the nanotube to nanotubes of the previous family. In part I of the paper, this quantitative comparison is formulated in our first main result as a discrete Saint-Venant principle. As a corollary, we also give a Liouville classification result. Our Saint-Venant principle can be derived for a large class of potentials (including the Lennard-Jones potential), when the perfect nanotubes at the equilibrium are stable. The approach is designed to be applicable to nanotubes that can have general shapes like, for instance, carbon nanotubes or DNA, under the oversimplified assumption that all the atoms are identical. In part II of the paper, we derive from our Saint-Venant principle a macroscopic mechanical model for general nanotubes. We prove that every solution is well approximated by the solution of a continuum model involving stretching and twisting, but no bending. We establish error estimates between the discrete and the continuous solution. More precisely we give two error estimates: one at the microscopic level and one at the macroscopic level.     

Nonlinear control for teleoperation systems with time varying delay

In this paper, we introduce delay-dependent control strategies for bilateral teleoperation systems in the presence of passive and constant input forces under time varying delay. We first design teleoperation systems where the local and remote sites are coupled by position signals of the master and slave manipulator. The design also combined undelayed position and velocity signals with nonlinear adaptive control terms to deal with the parametric uncertainties associated with the dynamical model of the master and slave manipulator. Then, we develop teleoperators by delaying position and velocity signals of the master and slave manipulator. Using Lyapunov–Krasovskii function, delay-dependent stability and tracking conditions for both teleoperators are developed in the presence of symmetrical and unsymmetrical time varying delays. The stability conditions are established in the presence of passive and constant human and environment interaction forces with the master and slave manipulators. Finally, simulation results are presented to demonstrate the validity of the theoretical development of the proposed designs for real-time teleoperation applications.     

Performance of various RANS eddy-viscosity models for turbulent natural convection in tall vertical cavities

The present study is dedicated to the identification of turbulence models that are accurate and numerically economic for computing the natural air-flow and heat transfer by convection in tall cavities with differentially heated vertical walls. The eddy-viscosity models (EVM) are among the simplest to implement and the most economical to treat this problem. This study evaluated the dynamic, thermal and computational performances of twenty EVM turbulence models with one, two or three-equation closure. All the models were first implemented in several in-house codes using the finite volume method. The predictions of the retained models in terms of profiles of velocity, temperature and vertical velocity fluctuations in the cavity have been compared with those of experimental or numerical studies. The obtained results were used to identify the turbulence models that are accurate and numerically economic in predicting natural convection in vertical cavities with a high aspect ratio. The EVM models with three-equation (v2-f and ζ-f) provide the most accurate mean and fluctuating quantities, followed by the k-ε RNG (ReNormalization Group) and k-ω SST (Shear Stress Transport) models. The computing time of these four models is higher than that of the 2L (two-layer) and q-ω models, which provide fairly accurate results especially for the mean heat transfer between the vertical active walls. The other one-equation (Spalart and Allmaras model) and two-equation (k-ε, k-ω and hybrid models) turbulence models tested in this work, have a high computing time and/or predictions that are not sufficiently precise simultaneously for both velocity and temperature fields.     

Influence of second sphere hydrogen bonding interaction on a manganese(II)-aquo complex

We have developed a pentadentate N(4)O ligand scaffold with a benzimidazole group placed in a rigid fashion to develop hydrogen bonding interaction with the ligand in the sixth position. The mononuclear Mn(II) complex with a water molecule was isolated and characterized. We discuss the role of the outer sphere ligand in stabilising a Mn(II)-aquo complex.