Thermogravimetric and Dielectric Relaxation Spectroscopy of a Thiosemicarbazide Schiff Base and its Metal Complexes

The thermal and dielectric spectroscopy of a thiosemicarbazide Schiff base and its nickel and palladium complexes were studied. The Perkin Elmer TGA7 thermal analysis technique was applied to study the effect of the heating rate on the TG curve. A Hioki 3520 RLC tester was used to measure the dielectric spectroscopy in the frequency range 10²–10⁵ Hz. The activation energies of the ligand and its complexes were determined, and the d.c. and a.c. conductivities were estimated for the ligand and its Ni(II) complex. The results showed that the Ni(II) complex was present in a dimeric form, while the Pd(II) complex was present in a monomeric form. The insertion of a nickel atom increases the d.c. conductivity. The mechanism of conduction is discussed.     

Effects of the dielectric discontinuity on the counterion distribution in a colloidal suspension

We introduce a new method for simulating colloidal suspensions with spherical colloidal particles of dielectric constant different from the surrounding medium. The method uses an approximate calculation of the Green function to obtain the ion-ion interaction potential in the presence of a dielectric discontinuity at the surface of the colloidal particle. The method is very accurate and is orders of magnitude faster than the traditional approaches based on series expansions of the interaction potential.     

Aryldiazonium silica sulfates as efficient reagents for Heck-type arylation reactions under mild conditions

An efficient and straightforward procedure for Heck-type arylation reactions was studied using aryldiazonium silica sulfates and olefins in the presence of a catalytic amount of Pd(OAc)₂. These reactions were carried out in water at room temperature without using a base or additional ligands. The use of a non-toxic solvent, a simple and clean work-up, short reaction times, and good yields are advantages of this method.     

Generalized Spiked Harmonic Oscillator in Non-commutative Space

In this paper non-commutative Schrodinger equation is considered for generalized Spiked harmonic oscillator potential. The energy shift due to non-commutativeity is obtained via the perturbation theory. Furthermore we show that the degeneracy of the initial spectral line is broken in transition from commutative space to non-commutative space.     

Does adiabatic quantum optimization fail for NP-complete problems?

It has been recently argued that adiabatic quantum optimization would fail in solving NP-complete problems because of the occurrence of exponentially small gaps due to crossing of local minima of the final Hamiltonian with its global minimum near the end of the adiabatic evolution. Using perturbation expansion, we analytically show that for the NP-hard problem known as maximum independent set, there always exist adiabatic paths along which no such crossings occur. Therefore, in order to prove that adiabatic quantum optimization fails for any NP-complete problem, one must prove that it is impossible to find any such path in polynomial time.     

Embedding Factorizations for 3‐Uniform Hypergraphs

In this article, two results are obtained on a hypergraph embedding problem. The proof technique is itself of interest, being the first time amalgamations have been used to address the embedding of hypergraphs. The first result finds necessary and sufficient conditions for the embedding a hyperedge‐colored copy of the complete 3‐uniform hypergraph of order m, , into an r‐factorization of , providing that . The second result finds necessary and sufficient conditions for an embedding when not only are the colors of the hyperedges of given, but also the colors of all the “pieces” of hyperedges on these m vertices are prescribed (the “pieces” of hyperedges are eventually extended to hyperedges of size 3 in by adding new vertices to the hyperedges of size 1 and 2 during the embedding process). Both these results make progress toward settling an old question of Cameron on completing partial 1‐factorizations of hypergraphs. © 2012 Wiley Periodicals, Inc. J. Graph Theory 73: 216–224, 2013     

An alternative approach for measuring the scattered acoustic pressure field of immersed single and multiple cylinders

The form function of an elastic target can be obtained from the scattered signal through a deconvolution process. The deconvolution process uses the signal measured from an acoustically hard target (reference signal) to compensate for the impulse response of the measurement system. In this paper, it is shown that this approach limits the usable frequency range of the signal and leads to inaccuracies in the final results. An alternative approach is proposed in which the reference signal is replaced by the specular echo. A procedure is described for extracting the specular echo from the measured signal even in cases where it is not completely isolated from the resonant components. Modifications are made to the existing deconvolution formulation and it is further extended to be applicable to multiple scattering measurements. Experimental results show that the new approach provides improved accuracy and wider usable frequency range in both single and multiple scattering experiments.     

Chirality Recognition of Selenium Compounds by NMR Spectroscopy in the Presence of a Chiral Dirhodium Complex

Abstract

Diastereomeric adducts of chiral soft-base selenium ligands with the enantiopure dirhodium complex Rh* allows stereodifferentiation by NMR spectroscopy of various nuclei (dirhodium method). The individual adduct species can be identified by low-temperature NMR spectroscopy.     

Silica Sulfuric Acid/Sodium Dichromate Dihydrate as an Efficient Heterogeneous Method for the Oxidation of Alcohols Under Mild Conditions

A combination of silica sulfuric acid and sodium dichromate dihydrate in the presence of wet SiO 2 were used as an effective oxidizing agent for the oxidation of alcohols to their corresponding aldehyde or ketone derivatives in dichloromethane or toluene with excellent yields.