Magnetotransport properties in \text{ Ni }_{81}\text{ Fe }_{19}\text{/Zr } multi-layers

In this work, we present a study of the magneto transport properties in magnetic multilayered structure $\text{ Ni }_{81}\text{ Fe }_{19}\text{/Zr }$ Ni 81 Fe 19 /Zr . The magnetic $(\text{ Ni }_{81}\text{ Fe }_{19})$ ( Ni 81 Fe 19 ) and non magnetic (Zr) layer thickness $(\mathbf{t}_\mathbf{NiFe}, \mathbf{t}_\mathbf{zr})$ ( t NiFe , t zr ) effects on the magneto resistance (MR) are discussed theoretically in the framework of the Johnson–Camley semi classical approach based on the Boltzmann transport equation. A comparison between calculated and measured MR is obtained. The observed MR ratio oscillates for Zr layer thickness with an average period of 7Å. A generally weak $\text{ MR }(\text{ t }_{\mathrm{NiFe}})$ MR ( t NiFe ) ratio for fixed $\mathbf{t}_\mathbf{zr}$ t zr is obtained and it shows a maxima peak of the MR with a value of 1.8 % located at $\mathbf{t}_\mathbf{NiFe}= 80$ t NiFe = 80 Å.     

Thermodynamic analysis of Si doping in GaN

Equilibrium calculations of Si-doping in GaN are investigated using the Gemini code. The method of the calculation is based on the minimisation of the Gibbs free energy. Experimental growth conditions are used for the calculation. The variables are the amount of the dopant and the temperature. The results show the formation of a solid Si₃N₄ compound with a certain quantity of the input SiH₄, that is the silicon precursor in our MOVPE system. Si₃N₄ formation can explain the limitation of Si incorporation and the surface roughening as revealed by MOVPE Si doped layers.     

The effect of increasing the excitation level of the sodium atom on the structure of the NaArn polyatomic exciplexes

In this work, the geometrical structures, the formation energies, and electronic states of the Na(ms)Ar_n polyatomic exciplexes with m = 3-6 and n = 2-5 are studied by using a quantum-classical method. The interaction potential between an electronically excited sodium atom and argon atoms are calculated by using a one-electron model involving electron-Ar and electron-Na⁺ pseudopotentials, in which the Hamiltonian is diagonalized at every optimization step in the Basin Hopping algorithm. The relationship between the position of the electronically excited levels and the cluster geometry is investigated as a function of the excitation level and of the spatial extension of the excited electron orbital. We show that the equilibrium structures of the ground state Na(3s)Ar_n and those of the electronically excited states Na(4s)Ar_n, Na(5s)Ar_n, and Na(6s)Ar_n are significantly different. As a result of the detailed examination of the relationships between the geometrical structure and density distribution of the Na valence electron of the Na^∗Ar_n with n = 2-5 polyatomic exciplexes, we can see that for the Na(4s)Ar_n polyatomic exciplexes, the two extreme geometries, neutral Na(3s)Ar_n and ionic Na⁺Ar_n compete. It appears that none of them is the actual one. For Na(5s)Ar_n and Na(6s)Ar_n the valence electron is very weakly bound to the ionic core and described by a more diffused orbital so that the geometry and the formation energies of this excited state called Rydberg states converge towards those of the ionic cores.     

Structural and lithium intercalation studies of Mn(0.5−x)CaxTi2(PO4)3 phases (0≤x≤0.50)

Materials from the Mn_(0.5−x)Ca_xTi₂(PO₄)₃ (0≤x≤0.50) solid solution were obtained by solid-state reaction in air at 1000 °C. Selected compositions were investigated by powder X-ray diffraction analysis, ³¹P nuclear magnetic resonance (NMR) spectroscopy and electrochemical lithium intercalation. The structure of all samples determined by Rietveld analysis is of the Nasicon type with the R space group. Mn²⁺/Ca²⁺ ions occupy only the M1 sites in the Ti₂(PO₄)₃ framework. The divalent cations are ordered in one of two M1 sites, except for the Mn_0.50Ti₂(PO₄)₃ phase, where a small departure from the ideal order is observed by XRD and ³¹P MAS NMR. The electrochemical behaviour of Mn_0.50Ti₂(PO₄)₃ and Mn_(0.5−x)Ca_xTi₂(PO₄)₃ phases was characterised in Li cells. Two Li ions can be inserted without altering the Ti₂(PO₄)₃ framework. In the 0≤y≤2 range, the OCV curves of Li//Li_yMn_0.50Ti₂(PO₄)₃ cells show two main potential plateaus at 2.90 and 2.50–2.30 V. Comparison between the OCV curves of Li//Li_(1+y)Ti₂(PO₄)₃ and Li//Li_yMn_0.50Ti₂(PO₄)₃ shows that the intercalation occurs first in the unoccupied M1 site of Mn_0.50Ti₂(PO₄)₃ at 2.90 V and then, for compositions y>0.50, at the M2 site (2.50–2.30 V voltage range). The effect of calcium substitution in Mn_0.50Ti₂(PO₄)₃ on the lithium intercalation is also discussed from a structural and kinetic viewpoint. In all systems, the lithium intercalation is associated with a redistribution of the divalent cation over all M1 sites. In the case of Mn_0.50Ti₂(PO₄)₃, the stability of Mn²⁺ either in an octahedral or tetrahedral environment facilitates cationic migration.     

A New Higher Order Shear Deformation Model for Static Behavior of Functionally Graded Plates

In this paper, a new displacement based high-order shear deformation theory is introduced for the static response of functionally graded plate. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Numerical illustrations concerned flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The validity of the present theory is investigated by comparing some of the present results with those of the classical, the first-order and the other higher-order theories. It can be concluded that the proposed theory is accurate and simple in solving the static behavior of functionally graded plates.     

A Spectrophotometric Method for the Determination of Buclizine Hydrochloride Using the Charge-Transfer Spectrum of Buclizine-Iodine Complex

Abstract

A simple and sensitive spectrophotometric method is described for the determination of buclizine hydrochloride in bulk and tablets form. The method is based on the formation of charge-transfer complex between buclizine, as n-donor, and iodine, as Δ acceptor, which measured spectrophotometrically at 295 and 355 nm. A Job's plot indicated a 1:1 complex between the drug and iodine and Beer's law was obeyed in a concentration range of 4–30 μg ml^?1. A more detailed investigation of the complex was made with respect to its association constant and the free energy change. The method is simple and sensitive and has been applied successfully to the analysis of laboratory-made tablets without any interference from the tablet excipients. To validate the method, the results obtained were compared statistically with a newly developed uv-derivative spectrophotometric method. The charge-transfer method was favored due to its higher sensitivity, cheap coast and available equipments.     

Laser interferometric study of the physical properties of transformer oil

This paper describes the optical, thermal, and electrical properties of an important nonpolar dielectric liquid, transformer oil. Applying dual laser (He–Ne and Argon laser of wavelengths 632.8 and 514.5 nm, respectively), and the Mach–Zehnder interferometric technique, the refractive indices and its temperature gradients are determined. Using Maxwell's and Cauchy's equations, the following optical, thermal, and electrical properties are calculated: optical and dielectric dispersion, optical permittivity and its thermal coefficient, thermal coefficient of volume expansion, specific refraction, specific dispersivity, characteristic impedance, electric susceptibility, and the variation of Cauchy's emperical constants with temperature. Additionally, different physical phenomena are studied as functions of wavelength and temperature.     

Mn doped ZnO nanostructured thin films prepared by ultrasonic spray pyrolysis method

Mn-doped ZnO thin films with different percentage of Mn content (0, 1, 3 and 5 at.%) and substrate temperature of 350 °C, were deposited by a simple ultrasonic spray pyrolysis method under atmospheric pressure. We have studied the structural and optical properties by using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and ultra-violet visible near infrared (UV–Vis-NIR) spectroscopy. The lattice parameters calculated for the Mn-doped ZnO from XRD pattern were found to be slightly larger than those of the undoped ZnO, which indicate substitution of Mn in ZnO lattice. Compared with the Raman spectra for ZnO pure films, the Mn-doping effect on the spectra is revealed by the presence of additional peak around 524 cm⁻¹ due to Mn incorporation. With increasing Mn doping the optical band gap increases indicating the Burstein–Moss effect.     

Quantum Steganography via Greenberger-Horne-Zeilinger GHZ_4 State

A quantum steganography communication scheme via Greenberger-Horne-Zeilinger GHZ 4 state is constructed to investigate the possibility of remotely transferred hidden information.Moreover,the multipartite entangled states are become a hectic topic due to its important applications and deep effects on aspects of quantum information.Then,the scheme consists of sharing the correlation of four particle GHZ4 states between the legitimate users.After insuring the security of the quantum channel,they begin to hide the secret information in the cover of message.Comparing the scheme with the previous quantum steganographies,capacity and imperceptibility of hidden message are good.The security of the present scheme against many attacks is also discussed.     

Ultrasound-Assisted Dispersive Microsolid-Phase Extraction for Preconcentration of Trace Cobalt and Nickel in Environmental Samples Prior to their Determination by Flame Atomic Absorption Spectrometry

Journal of Applied Spectroscopy - A new, green, simple, and validated ultrasound-assisted dispersive microsolid-phase extraction method applying unprecedented adsorbent-modified multiwalled carbon...