Experiment and prediction of a cavity type separated flow

A detail study involving flow visualization, Laser Doppler Velocimeter (LDV) measurements and numerical prediction is presented. The visualization experiments revealed striking results of a pulsatile motion in the separated flow region associated with the formation and passage of large eddy structures. Measurements of mean velocities and turbulence intensity profiles across the separated flow field, provided information about the separated shear layer development and the recirculating flow pattern. The numerical predictions, obtained with a two-layer turbulence model in conjunction with the SIMPLE algorithm, failed to reproduce the coherent eddies and the pulsatile motion, but the mean velocities are reasonably reproduced.     

A generalization of a theorem of Lewy on harmonic mappings

It is shown that every one-to-one pluriharmonic mapping of a neighborhood of 0 R⁴ into itself has nonvanishing Jacobian.Translated from Matematicheskii Zametki, Vol. 13, No. 2, pp. 189–194, February, 1973.In conclusion, the author wishes to thank B. V. Shabat and E. M. Chirka for their help with this work.     

A modified Chebyshev ϑ‐weighted Crank–Nicolson method for analyzing fractional sub‐diffusion equations

This study presents a robust modification of Chebyshev ? ‐weighted Crank–Nicolson method for analyzing the sub‐diffusion equations in the Caputo fractional sense. In order to solve the problem, by discretization of the sub‐fractional diffusion equations using Taylor's expansion a linear system of algebraic equations that can be analyzed by numerical methods is presented. Furthermore, consistency, convergence, and stability analysis of the suggested method are discussed. In this framework, compact structures of sub‐diffusion equations are considered as prototype examples. The main advantage of the proposed method is that, it is more efficient in terms of CPU time, computational cost and accuracy in comparing with the existing ones in open literature.     

The hydrophilic interaction like properties of some reversed phase high performance liquid chromatography columns in the analysis of basic compounds

The hydrophilic interaction chromatography (HILIC) like properties of an ACE cyano (CN) HPLC column was studied for the separation of some basic compounds. Good separation of a test mix of basic compounds was obtained with a mobile phase consisting of acetonitrile/water (95:5) containing 3.25 mM ammonium acetate. The retention times of the basic compounds decreased with increased ionic strength or with increased water content in the mobile phase. When Trishydroxymethyl aminomethane (Tris) (pK(a) 8.0), which is a weaker amine than ammonia (pK(a) 9.3), was used as an additive in the mobile phase retention of the basic compounds was increased. The ACE CN column gave excellent peak shapes for all the basic compounds. The utility of the column for impurity profiling of two basic drugs was tested and some impurities in oxprenolol were characterised by interfacing with Fourier transform mass spectrometry. It was also observed that ACE butyl and ACE phenyl columns retained basic compounds when the columns were eluted with a mobile phase consisting of acetonitrile/water (95:5) containing 3.25 mM ammonium acetate.     

Diastereoselective synthesis of 5-iminooxazolines and their subsequent transformation to α,α-disubstituted dipeptide esters: a formal [4+1] cycloaddition reaction of cyclohexyl isocyanide and Z-alkyl-α-benzoyl amino-acrylates

A novel atom economical diastereoselective synthesis of 5-iminooxazolines and their subsequent transformation to α,α-disubstituted dipeptide esters is described. Heating a mixture of cyclohexyl isocyanide and Z-α-benzoyl amino-acrylic acid alkyl esters under solvent-free conditions, afforded 5-iminooxazolines, which, upon specifications provided α,α-disubstituted dipeptide esters in good yield.     

A novel sensor for simultaneous determination of dopamine and uric acid using a new MFI-type zeolite prepared by microwave-assisted synthesis

Abstract  

This paper describes microwave-assisted synthesis of a new MFI-type zeolite, Zeolite Secony Mobile (ZSM-5), its characterization by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), and its application for fabrication of a modified carbon paste electrode. This novel electrode was employed for sensitive and simultaneous determination of dopamine and uric acid at biological pH (pH 7.0). The results show that this zeolite-modified carbon paste electrode significantly improves the electron transfer rate and reduces the overpotential of dopamine and uric acid oxidation without any fouling effect due to deposition of their oxidized products. The linear analytical curves were obtained in the ranges of 9.0 × 10⁻⁶–4.9 × 10⁻⁴ and 8.0 × 10⁻⁶–9.0 × 10⁻⁴ M for dopamine and uric acid, respectively, by using differential pulse voltammetry based on oxidation of these biomolecules. The detection limits (2σ) were determined for dopamine and uric acid as 7.9 × 10⁻⁶ and 7.1 × 10⁻⁶ M, respectively. This method has been successfully employed for quantification of dopamine and uric acid in real samples.     

A lupane triterpenoid and other constituents of Salvia eremophila

Phytochemical investigation of the aerial parts of Salvia eremophila led to the isolation of a lupane triterpenoid, 3β, 20-dihydroxylupane-28-oic acid (1), together with eight other compounds, comprising three diterpene, two triterpene, two flavonoids and a steroidal glucoside. Their structures were elucidated by interpretation of their one-dimensional and two-dimensional NMR spectra and completed by the analysis of the HRESIMS data. Compounds 1, 2-4 and 8 were evaluated for their cytotoxicities against five human tumour cell lines. Compounds 1 and 3 hold a good potential for use in future studies due to their anti-cancer properties.     

Thermomechanical coupling of geometrically non-coherent interfaces

An evacuated tube collector is composed of a vacuum glass tube forged to a metal tube creating an interface which undergoes thermomechanical cyclic loading. To numerically model such a thermomechanical and geometrically non-coherent interface, a decohesion element with mixed-mode capability, based on a normal-shear decomposition of the displacement discontinuity vector is used, exploiting exponential traction-separation laws. In addition to the classical strategies, interfacial elements are allowed to have an in-plane stretch resistance by assuming a thermohyperelastic interface Helmholtz energy, a function of the rank-deficient interface deformation gradient and temperature , as an extension of the surface/interface elasticity theory. The nonlinear governing equations are given and solved using the finite element method. The results are illustrated through a series of numerical examples for different material parameters. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Description of 160Dy nucleus by partial dynamical SU(3) symmetry

We considered the characteristic features of SU(3) partial dynamical symmetry in the interacting boson model framework to show the relevance of such intermediate symmetry structure in the nuclear spectroscopy of the ¹⁶⁰Dy nucleus. The predictions of SU(3)-PDS for the energy spectrum and the transition probabilities were compared with the most recent experimental data and an acceptable degree of agreement was achieved.