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Shoair A.G.F.,Damiatta University
Journal of Coordination Chemistry | Year: 2012

Copper(II) complexes [Cu(L)2]nH2O, where L is 3-(p-X-)-4-hydroxy-l,2- naphthoquinone (for L1, X=H; L2, X=CH3; L3, X=Cl; L4, X=Br; and L5, X=NO2), have been synthesized and characterized by analytical, electrochemical, spectroscopic (IR, UV-Vis, ESR, and 1H NMR), and magnetic methods. From the data obtained, square-planar geometry has been assigned for all the complexes. [CuL1]H2O exhibits catalytic activity for oxidation of benzyl alcohol, piperonyl alcohol, and cinnamyl alcohol into their respective aldehydes in the presence of H2O2 as co-oxidant and in CH3CN and H2O as solvents at room temperature. © 2012 Copyright Taylor and Francis Group, LLC. Source


El-Shahawi M.S.,King Abdulaziz University | El-Shahawi M.S.,Damiatta University | Al-Jahdali M.S.,King Abdulaziz University | Bashammakh A.S.,King Abdulaziz University | And 2 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

(Graph Presented)The ligation behavior of bis-benzoin ethylenediamine (B2ED) and benzoin thiosemicarbazone (BTS) Schiff bases towards Ru3+, Rh3+, Pd2+, Ni2+ and Cu 2+ were determined. The bond length of M-N and spectrochemical parameters (10Dq, b, B and LFSE) of the complexes were evaluated. The redox characteristics of selected complexes were explored by cyclic voltammetry (CV) at Pt working electrode in non aqueous solvents. Au mesh (100 w/in.) optically transparent thin layer electrode (OTTLE) was also used for recording thin layer CV for selected Ru complex. Oxidation of some complexes occurs in a consecutive chemical reaction of an EC type mechanism. The characteristics of electron transfer process of the couples M2+/M3+ and M 3+/M4+ (M = Ru3+, Rh3+) and the stability of the complexes towards oxidation and/or reduction were assigned. The nature of the electroactive species and reduction mechanism of selected electrode couples were assigned. © 2013 The Authors. Published by Elsevier B.V. All rights reserved. Source


El-Shahawi M.S.,Damiatta University | El-Shahawi M.S.,King Abdulaziz University | Kadi M.W.,King Abdulaziz University | El-Khouly S.H.,Egypt Atomic Energy Authority | And 3 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2013

A low cost and selective method has been developed for the separation of trace concentrations of 90Y3+ from its parent 89Sr2+. The proposed procedure is based upon complete retention of 90Y3+ onto zirconium-vanadate (Zr-V) gel ion exchanger packed column from aqueous solutions containing HCl (1.0 × 10-5mol dm-3). Under these conditions, 89Sr2+ species were not retained onto Zr-V sorbent. The retained 90Y3+ species were then recovered with HCl. The performance of Zr-V sorbent packed column was determined via the height equivalent to the theoretical plates (HETP) and the number of plates (N). Validation of the developed method was checked by calculating the radionuclidic purity in terms of purification factor (P f = A/A0) and radiochemical purity of the eluted 90Y from the column. Zr-V sorbent packed column offers unique advantages of retention and quantitative separation of 90Y from retention over conventional solid sorbents in rapid and effective separation of trace concentration of 90Y3+ from 89Sr2+ in their aqueous equilibrium media. © 2012 Akadémiai Kiadó, Budapest, Hungary. Source


Elhagary M.A.,Damiatta University
International Journal of Thermophysics | Year: 2013

A one-dimensional problem for a viscoelastic half space is considered in the context of the generalized theory of thermoviscoelasticity with one relaxation time. The bounding plane is acted upon by a combination of thermal and mechanical shock acting for short times. The Laplace transform technique is used to solve the problem. The solution in the transformed domain is obtained by a direct approach. The inverse transforms are obtained in an approximate analytical manner using asymptotic expansions valid for small values of time. The temperature, displacement, and stress are computed and represented graphically. © 2013 Springer Science+Business Media New York. Source


Ahmad W.,King Abdulaziz University | Al-Sibaai A.A.,King Abdulaziz University | Bashammakh A.S.,King Abdulaziz University | Alwael H.,King Abdulaziz University | And 2 more authors.
TrAC - Trends in Analytical Chemistry | Year: 2015

Dispersive liquid-liquid microextraction (DLLME) techniques have attracted considerable interest because they are cost effective, easy to operate, and reliably preconcentrate trace levels of analytes in complex matrices. This comprehensive review is concerned with principles, applications and developments of DLLME techniques for analysis of trace emerging pesticides in water. DLLME techniques have had few couplings to spectrofluorimetric methods and relatively none with electrochemical techniques. We highly recommend thin-layer stripping voltammetric techniques at surface-modified electrodes and spectrofluorimetric techniques coupled and implemented with DLLME. Great attention should be focused on developing low-cost, precise methods for analysis of trace concentrations of pesticides in various biological and environmental samples. We describe milestones and the combination of nanotechniques in the DLLME field, green aspects, advantages and shortcomings of known DLLME protocols. © 2015. Source

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