AlCl3 as an Effective Lewis Acid for the Synthesis of Arylaminotetrazoles

An efficient method for preparation of the arylaminotetrazoles derivatives is reported using aluminium chloride as an effective Lewis acid. Generally, 5-arylamino-1H-tetrazole isomer can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring. As the electropositivity of the substituent is increased, the product is shifted toward the formation of 1-aryl-5-amino-1H-tetrazole isomer.     

A theoretical study on the importance of steric effects,electronic properties,interaction and solvation energies in the ‘host–guest’ chemistry of protonated azacryptands and halide anions

It is well known that the selectivity of a receptor for an anion depends on the compatibility of the cavity size of the receptor and the size of the anion. In this work the macrobicyclic [H₆L(X)]⁵⁺ (X⁻=F, Cl, Br); are studied theoretically and compared with [H₆L′(F)]⁵⁺ having a smaller cavity size. It was shown that the ideal match between the sizes of the protonated azacryptand and the fluoride ion exists in the [H₆L′(F)]⁵⁺ complex but the [H₆L]⁶⁺ is a better receptor than [H₆L′]⁶⁺ in solution. Thus the results clearly indicate that in some special cases a better receptor is not one whose cavity size has better compatibility with the anion size.     

Three-dimensional free vibration analysis of four-parameter continuous grading fiber reinforced cylindrical panels resting on Pasternak foundations

This research investigates three-dimensional free vibration analysis of four-parameter continuous grading fiber reinforced (CGFR) cylindrical panels resting on Pasternak foundations by using generalized power-law distribution. The functionally graded orthotropic panel is simply supported at the edges, and it is assumed to have an arbitrary variation of matrix volume fraction in the radial direction. A four-parameter power-law distribution presented in literature is proposed. Symmetric and asymmetric volume fraction profiles are presented. Suitable displacement functions that identically satisfy the boundary conditions at the simply supported edges are used to reduce the equilibrium equations to a set of coupled ordinary differential equations with variable coefficients, which are solved by generalized differential quadrature method, and natural frequency is obtained. The fast rate of convergence of the method is demonstrated, and to validate the results, comparisons are made with the available solutions for functionally graded isotropic shells with/without elastic foundations. The effect of the elastic foundation stiffness parameters and various geometrical parameters on the vibration behavior of the CGFR cylindrical panels is investigated. This work mainly contributes to illustrate the influence of the four parameters of power-law distributions on the vibration behavior of functionally graded orthotropic cylindrical panels resting on elastic foundation. This paper is also supposed to present useful results for continuous grading of matrix volume fraction in the thickness direction of a cylindrical panel on elastic foundation and comparison with similar discrete laminated composite cylindrical panel.     

Pyrolytic graphite electrode modified with a thin film of a graphite/diamond nano-mixture for highly sensitive voltammetric determination of tryptophan and 5-hydroxytryptophan

We have prepared a pyrolytic graphite electrode (PGE) whose surface is covered with a thin film of a nano-mixture of graphite/diamond (NGD). The electrode is shown to be capable of electrochemically sensing of tryptophan (TRP) and 5-hydroxytryptophan (HTRP). The presence of the NGD film resulted in a remarkable increase in the peak currents and sharpness of the waves so that submicromolar concentrations of TRP and HTRP become detectable. Potential scan rates, the pH of the solution, the accumulation conditions and the amount of the modifier were optimized via cyclic voltammetry. Linear sweep voltammetry, under optimized accumulation time and in open circuit operation, was applied to the determination of TRP and HTRP with detection limits (S/N = 3) of 30 nM (TRP) and 6 nM (HTRP). The electrode can be easily prepared, displays high sensitivity, sharp peaks, long-term stability, and remarkable voltammetric reproducibility and repeatability. These properties make the sensor suitable for the trace analysis of TRP and HTRP in pharmaceutical and clinical preparations.

A pyrolytic graphite electrode modified with a thin film of a nano-mixture of graphite/diamond. This electrochemical sensor applied for determination of tryptophan and 5-hydroxytryptophan in aqueous solutions. The modified electrode showed a remarkable increase in the peak currents and sharpness of the waves.

     

Nonperturbative entangling gates between distant qubits using uniform cold atom chains

We propose a new fast scalable method for achieving a two-qubit entangling gate between arbitrary distant qubits in a network by exploiting dispersionless propagation in uniform chains. This is achieved dynamically by switching on a strong interaction between the qubits and a bus formed by a nonengineered chain of interacting qubits. The quality of the gate scales very efficiently with qubit separations. Surprisingly, a sudden switching of the couplings is not necessary. Moreover, our gate mechanism works for multiple gate operations without resetting the bus. We propose a possible experimental realization in cold atoms trapped in optical lattices and near field Fresnel trapping potentials.     

Nature of metal–NHC bonds in some potential anticancer [(NHC(R))2→M]+ (M = CuI,AgI, AuI,R = n-propyl,n-butyl,n-pentyl,n-hexyl,n-heptyl,n-octyl,n-nonyl,n-decyl) complexes

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Efficient synthesis of new functionalized 2-(alkylamino)-3-nitro-4-(aryl)-4H-benzo[g]chromene-5,10-dione

Molecular Diversity - Structurally diverse benzo[g]chromenes were conveniently synthesized by one-pot, multi-component reaction of N-alkyl-1-(methylthio)-2-nitroethenamine (derived from the...     

Symmetric designs and projective special linear groups of dimension at most four

In this article, we study symmetric $\left(v,k,\lambda \right)$ designs admitting a flag‐transitive and point‐primitive automorphism group $G$ whose socle is isomorphic to a projective special linear group of dimension at most four. We, in particular, determine all such possible parameters $\left(v,k,\lambda \right)$ and show that such a design belongs to one of two infinite families of point‐hyperplane designs or it is isomorphic to a design with parameters (7, 3, 1), (7, 4, 2), (11, 5, 2), (11, 6, 3), (15, 8, 4), (35, 18, 9), or (56, 45, 18).     

Numerical analysis of effect of nanofluid and fin distribution density on thermal and hydraulic performance of a heat sink with drop-shaped micropin fins

Journal of Thermal Analysis and Calorimetry - In the present study, the effect of nanofluid and distribution density of fin on thermal–hydraulic performance of a heat sink with drop-shaped...     

Semi-analytical solution for three-dimensional vibration of thick continuous grading fiber reinforced (CGFR) annular plates on Pasternak elastic foundations with arbitrary boundary conditions on their circular edges

In this paper free vibration of continuous grading fiber reinforced (CGFR) annular plates on an elastic foundation, based on the three-dimensional theory of elasticity, for different boundary conditions at the circular edges is investigated. The foundation is described by the Pasternak or two-parameter model. The CGFR annular plates have an arbitrary variation of fiber volume fraction in the thickness direction. A semi-analytical approach composed of differential quadrature method (DQM) and series solution is adopted to solve the equations of motion. The fast rate of convergence of the method is demonstrated and comparison studies are carried out to establish its very high accuracy and versatility. Some new results for the natural frequencies of the plate are prepared, which include the effects of elastic coefficients of foundation, boundary conditions, material and geometrical parameters. Besides, results for CGFR plate with arbitrary variation of fiber volume fraction in the thickness direction of the plate are compared with discrete laminated composite plate. The main contribution of this work is to present useful results for continuous grading of fiber reinforcement in the thickness direction of a plate on an elastic foundation and comparison with similar discrete laminated composite plate. The interesting and new results show that non-dimensional natural frequency parameters of a functionally graded fiber volume fraction is larger than that of a discrete laminated and close to that of a 2-layer. The new results can be taken as the benchmark solutions for those from numerical methods and future researches.