Effect of Mechanical Stresses and Annealing on the Magnetic Structure and the Magnetic Impedance of Amorphous CoFeSiBCr Microwires

The structural and magnetic properties of amorphous ferromagnetic microwires can undergo significant measurements under the action of external mechanical stresses and heat treatment. The study of transformations occurring in this case is important for designing various sensors of mechanical stresses, loading, and temperature and also for inducing in the wires a certain type of magnetic anisotropy that plays a significant role in the realization of various effects in them. In this work, the influence of external stresses and annealing on the processes of the magnetization and the magnetic impedance of Co₇₁Fe₅B₁₁Si₁₀Cr₃ microwires having a low positive magnetostriction (~10^-8) in amorphous state has been studied. The influence of external stresses leads to a sharp change in the character of the magnetization reversal curve, which was due to the change in the sign of the magnetostriction and the type of magnetic anisotropy. The amplitude of higher harmonics and the value of the magnetic impedance, respectively, are sensitive to mechanical stresses. Elastic stresses in the wires with a partial crystallization do not lead to a marked change in the magnetic properties; however, annealing can lead to a substantial increase in the axial magnetic anisotropy of the wires existing in the stressed state. The experimental results are analyzed in the framework of a magnetostriction model of induced magnetic anisotropy.     

Printed Planar Antenna for Wideband Applications

A compact planar antenna operating at a frequency range of 3–16 GHz is presented for wideband applications. The antenna is composed of a square patch fed by a microstrip line and a partial ground plane with a rectangular slot. The proposed antenna is very easy to be integrated with microwave circuitry for low manufacturing cost. The flat antenna has a compact structure and the total size is 29 mm × 22 mm. The result shows that the measured impedance bandwidth (VSWR≤ 2) of the proposed antenna is 3.2–15.44 GHz, with a notch from 4.7 to 5.8 GHz. The effects of the structure parameters on impedance bandwidth are also investigated. Details of the proposed compact planar antenna design are presented and discussed.     

Highly efficient and catalyst-free synthesis of unsymmetrical thioureas under solvent-free conditions

A highly efficient and simple synthesis of unsymmetrical thioureas is reported based on the reaction of readily synthesized dithiocarbamates with amines, without using any catalyst under solvent-free conditions. The short reaction time, high yields, and solvent-free conditions are advantages of this method. We did not observe the formation of any symmetric disubstituted thiourea, under these reaction conditions.     

Silica Aerogel: Synthesis,Characterization, Applications,and Recent Advancements

Silica aerogels have drawn considerable attention due to their low density (almost 95% of the total volume is composed of air), hydrophobicity, optical transparency, low conductivity of heat, and large surface to volume ratio. Sol–gel processing is used to prepare aerogels from molecular precursors. To replace the pore fluid with air while retaining the solid network, a supercritical drying process (the most frequent approach) is used. However, recent technologies use atmospheric pressure to allow for liquid removal followed by chemical alteration of the gel's internal layer, which leaves only a silica network with a porous structure filled with air. This study discusses the sol–gel method for preparing silica aerogels and their various drying processes. Furthermore, various areas of applications of silica aerogels, including electronics, construction, aerospace, purification of water and air, sensing, catalyst, biomedical, absorbent, food packing, textile, etc., are also discussed. Lastly, this review provides a perception of the recent scientific progress along with the futuristic development of silica aerogel.     

Non-carcinogenic health risk assessment of nitrate in bottled drinking waters sold in Iranian markets: A Monte Carlo simulation

Accreditation and Quality Assurance - The main objective of the current research was to evaluate nitrate content in different brands of bottled drinking waters sold in Iranian markets using the...     

Dynamic meshless method applied to nonlocal crack problems

The dynamic meshless methods for local and nonlocal field theories are formulated in this paper. Application to two crack problems is presented. The meshless method of local theory gives solution that is in good agreement with the classical analytical crack tip solution, while the nonlocal theory yields a solution without stress singularity at the crack tip. The numerical results also show the embedded nonlocal nature of meshless methods.     

Facile Synthesis and Characterization of Monocrystalline Cubic ZrO2.12 Nanoparticles

Non-stoichiometric zirconium oxide nanocrystals with the formula of ZrO_2.12 and diameters less than 10 nm were synthesized in the course of calcination of a dried solution of zirconium(IV) oxy nitrate in the presence of citric acid at 600 °C for 5 h. Crystallite size of product was increased to 20 nm when starch was used as emulsifier. Effect of the organic additive, which was equal of moles of the nitrate ions of the zirconium precursor, was investigated on phase formation, morphology and particle size of products. Samples were characterized by FT-IR, TG/DTA, SEM and TEM analysis. Phase structure of samples were also analysed by the powder X-ray diffraction.     

Analysis of sub-picogram quantities of 238Pu by thermal ionization mass spectrometry

Journal of Radioanalytical and Nuclear Chemistry - A multiple ion-counting total evaporation technique has been developed for precise analysis of sub-picogram (pg) quantities of 238Pu by thermal...     

DFT Study of the Geometrical and Electronic Structures of Geminal Dicationic Ionic Liquids 1,3‐Bis[3‐methylimidazolium‐1‐yl]hexane Halides

In this work, the geometrical and electronic properties of the mono cationic ionic liquid 1‐hexyl‐3‐methylimidazolium halides ([C₆(mim)]⁺_X^?, X=Cl, Br and I) and dicationic ionic liquid 1,3‐bis[3‐methylimidazolium‐1‐yl]hexane halides ([C₆(mim)₂X₂], X=Cl, Br and I) were studied using the density functional theory (DFT). The most stable conformer of these two types ionic liquids (IL) are determined and compared with each other. Results show that in the most stable conformers, in both monocationic ILs and dicationic ILs, the Cl^? and Br^? anions prefer to locate almost in the plane of the imidazolium ring whereas the I^? anion prefers nearly vertical location respect to the imidazolium ring plan. Comparison of hydrogen bonding and ionic interactions in these two types of ionic liquids reveals that these ionic liquids can be formed hydrogen bond by Cl^? and Br^? anion. The calculated thermodynamic functions show that the interaction of cation — anion pair in the dicationic ionic liquids are more than monocationic ionic liquids and these interactions decrease with increasing the halide anion atomic weight.