First magnets based on thiocyanato-bridges

2-D NCS-bridged {3d-4d} molecule-based magnets, formed by reaction of [Mo(III)(NCS)(6)](3-) with either Ni(II) or Co(II) complexes, have been found to exhibit magnetic ordering with T(C) = 39 K for {Co(3)Mo(2)} while {Ni(3)Mo(2)} has a non-magnetic ground state as a result of exact compensation by the individual sub-lattices.     

Construction of $${\text {MDS}}$$ MDS matrices from generalized Feistel structures

Designs, Codes and Cryptography - This paper investigates the construction of $${\text {MDS}}$$ matrices with generalized Feistel structures ( $${\text {GFS}}$$ ). The approach developed by this...     

Acoustic radiation from a submerged hollow FGM sphere

An exact study based on the linear theory of elasticity is presented for the steady-state sound radiation characteristics of an arbitrarily thick radially inhomogeneous elastic isotropic hollow sphere, immersed in and filled with ideal compressible fluids, and subjected to an arbitrary axisymmetric time-harmonic driving force at its internal surface. A modal state equation with variable coefficients is set up in terms of appropriate displacement and stress functions and their spherical harmonics by means of the laminated approximation approach. Taylor’s expansion theorem is subsequently employed to solve the modal state equation, ultimately calculating a global transfer matrix. Numerical results are presented for a water-submerged/air-filled steel/zirconia FGM hollow sphere under an axisymmetric distributed internal pressure force. The effects of shell wall thickness, the material compositional gradient, frequency, and subtended polar angle of the internal pressure force on the far-field radiated pressure directivity patterns as well as the total radiated power are examined. It is demonstrated that the material gradient can significantly change the acoustical characteristics of hollow inhomogeneous sphere, especially for thick shells at high excitation frequencies. Limiting cases are considered and good agreements with available results as well as with the computations made by using a finite element package are obtained.     

Synthesis of micro and nanostructured MnO2 and their comparative study in lithium battery

Micro and nanostructured ??-MnO₂ are synthesized to investigate the size effect of cathode active materials in battery performance. MnSO₄ and (NH₄)₂S₂O₈ were used as starting materials to prepare micro and nanostructured samples in the presence of stirring and ultrasonic irradiation, respectively. Structure optimization is done by changing values for temperature and manganese sulphate concentration. The MnO₂ micro and nanoparticles are characterized by scanning electron microscopy and X-ray diffraction (XRD). The XRD results reveal that only ??-MnO₂ is formed under the reaction conditions. Under the optimized conditions, manganese dioxide nanoparticles, with an average particle size of 56?nm, are obtained. Both micro and nanostructured MnO₂ is used as the cathode active material in Li/MnO₂ battery. Discharge profiles of stirrer-based cathode material (micro) and ultrasonic instrument-based one (nano) compared with each other in constant discharge currents of 50 and 100?mA?g^?1. The results demonstrated that nanosized materials show higher specific capacities and energies. Electrochemical impedance spectroscopy is used to investigate the size effect of cathode material on battery resistance and the results show a copious decrease in total resistance.     

Electrochemical behaviors of novel electroactive Au nanoparticles protected by self-assembled monolayers

There has been substantial recent interest in studying monolayer-protected gold clusters (MPCs) owing to their diverse applications. The present work is an electrochemical study of novel gold nanoparticles covered with a monolayer of mercapto-dodecanol ended chloro-dicyano-quinone (HS-C12O-CDQ), which was adsorbed on the electrode (CDQ-MPCs film). Our findings reveal a redox behavior for CDQ-MPCs film similar to the solution electrochemistry of dichloro-dicyano-quinone. Furthermore, a diffusion-like mechanism was found for electron transfer, which may have occurred due to proton diffusion towards or outwards the electrode through the film casted. Chronoamperometry confirmed diffusion behavior of the ET process. Finally, EIS was used to find the rate constant of ET process for the redox reaction that occurred and the contribution of MPCs in total interfacial capacitance.     

Effect of “Magnetized Water” on Size of Nickel Oxide Nanoparticles and their Catalytic Properties in Co2 Reforming of Methane

Theoretical and Experimental Chemistry - It was shown that the particle size of NiO nanoparticles has been controlled through the homogeneous precipitation process by using “magnetized...     

An Improvement of Ostrowski’s and King’s Techniques with Optimal Convergence Order Eight

In this paper, we first establish a new class of three-point methods based on the two-point optimal method of Ostrowski. Analysis of convergence shows that any method of our class arrives at eighth order of convergence by using three evaluations of the function and one evaluation of the first derivative per iteration. Thus, this order agrees with the conjecture of Kung and Traub (J. ACM 643–651, 1974) for constructing multipoint optimal iterations without memory. We second present another optimal eighth-order class based on the King’s fourth-order family and the first attained class. To support the underlying theory developed in this work, we examine some methods of the proposed classes by comparison with some of the existing optimal eighth-order methods in literature. Numerical experience suggests that the new classes would be valuable alternatives for solving nonlinear equations.     

Selectfluor promoted environmental-friendly synthesis of 2H-chromen-2-ones derivatives under various reaction conditions

A simple, clean and benign route to the synthesis of 2H-chromen-2-ones derivatives through one-pot condensation of ??-ketoesters and substituted phenols in the presence of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bistetrafluoroborateis (Selectfluor? F-TEDA-BF₄) as catalyst under solvent free reaction conditions was experimented. The application of ultrasonic irradiation improved the yields and reduced the reaction times. The use of selectfluor catalyst is feasible because of its stability, commercial value, easy handling, easy recovery and good activity. To extend our research, the ability of selectfluor for the synthesis of 2-aminochromene derivatives was also examined.