Solving System of Conformable Fractional Differential Equations by Conformable Double Laplace Decomposition Method

Herein, an approach known as conformable double Laplace decomposition method (CDLDM) is suggested for solving system of non-linear conformable fractional differential equations. The devised scheme is the combination of the conformable double Laplace transform method (CDLTM) and, the Adomian decomposition method (ADM). Obtained results from mathematical experiments are in full agreement with the results obtained by other methods. Furthermore, according to the results obtained we can conclude that the proposed method is efficient, reliable and easy to be implemented on related many problems in real-life science and engineering.     

Identification of an artifact peak co-eluting with formaldehyde-2,4-dinitrophenylhydrazone derivative by GC-MS and chemometrics

A chemometric approach was utilized to identify an artifact peak co-eluting with formaldehyde-2,4-dinitophenylhydrazone. Application of the methods of principal component analysis to the mass spectra of the formaldehyde-hydrazone peaks collected at 200-280 °C has revealed the presence of two factors contributing to these spectra. Moreover, the use of self-modeling curve resolution (SMCR) techniques has enabled the reconstruction of the spectra of the pure components. One of the identified components that contribute to the spectra of the mixture was formaldehyde-2,4-dintrophenylhydrazone, whereas the other component was 1-amino-2,4-dinitrobenzene, a degradation product of 2,4-dintrophenylhydrazine.     

Flow injection spectrophotometric determination of the antibiotic ciprofloxacin in drug formulations.

A flow injection spectrophotometric method for the assay of ciprofloxacin was developed. The method was based on the chelation of iron(III) with the drug in 0.023 mol dm-3 sulfuric acid solution in a 72 cm long coil and the brown-red complex produced was monitored at 447 nm. The super modified simplex computer program was employed for the optimization of the system and chemical parameters with respect to throughput and sensitivity as a measure of system performance. A working range for ciprofloxacin determination of 50-500 ppm for a 110 mm3 sample size with an optimum of 250 samples per hour was achieved with a relative standard deviation of less than 0.92%. The method was successfully applied to the determination of ciprofloxacin in drug formulations.     

Ion-association method for the spectrophotometric determination of the antitussive drug noscapine

A simple, sensitive and fairly rapid method for the determination of noscapine is described, based on the measurement of the absorbance of the organic soluble ion-association complex formed between the noscapine monocation and a bulky counter anion. Methyl Orange, Bromothymol Blue and Bromocresol Green (BCG) were examined as counter ions. The effect of few solvents, the counter-ion concentration and pH on the extraction were also investigated. The most suitable system was based on BCG (pH 3.0) with chloroform as the extraction solvent. The use of the other counter ions, in conjunction with their respective solvents, was found to be less sensitive. The BCG system exhibits negligible or no interference when used for the determination of 38 ppm of noscapine in the presence of several drug excipients, thus lending itself as a possible procedure for the determination of this alkaloid in pharmaceutical preparations.     

Development of a selective fluorimetric technique for rapid trace determination of zinc using 3-hydroxyflavone

A sensitive and a selective spectrofluorimetric method have been developed for the rapid determination of trace levels of zinc. The method is based on complex formation between zinc and 3-hydroxyflavone (3HF), which displays an intense emission signal around 478 nm. The analytical performance of the method was examined by considering the factors that affect the complex formation such as pH, mole ratio of the metal and solvent type. The optimum conditions for the complex formation were metal to ligand stoichiometric ratio of 1:1 at pH 7.5 with 0.1 M Tris buffer. Under these conditions the detection limit attained was 1.5 ppb. The method was appropriately validated and yielded relative standard deviations of less than 2% (n = 5), which was considered acceptable. It was successfully applied to the trace determination of zinc in drinking water, hair shampoo and pharmaceutical samples.     

Utilizing NMR and EPR spectroscopy to probe the role of copper in prion diseases

Copper is an essential nutrient for the normal development of the brain and nervous system, although the hallmark of several neurological diseases is a change in copper concentrations in the brain and central nervous system. Prion protein (PrP) is a copper‐binding, cell‐surface glycoprotein that exists in two alternatively folded conformations: a normal isoform (PrP^C) and a disease‐associated isoform (PrP^Sc). Prion diseases are a group of lethal neurodegenerative disorders that develop as a result of conformational conversion of PrP^C into PrP^Sc. The pathogenic mechanism that triggers this conformational transformation with the subsequent development of prion diseases remains unclear. It has, however, been shown repeatedly that copper plays a significant functional role in the conformational conversion of prion proteins. In this review, we focus on current research that seeks to clarify the conformational changes associated with prion diseases and the role of copper in this mechanism, with emphasis on the latest applications of NMR and EPR spectroscopy to probe the interactions of copper with prion proteins. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and Reactions of Some New Thienopyrimidines

4-Methyl-6-mercapto-2-phenylpyrimidine-5-carbonitrile ( 1 ) was reacted with different halo compounds, namely ethylchloroacetate, chloroacetone, bromoacetanilide, p-chlorobromoacetanilide, and p -methoxy chloroacetanilide in ethanol in the presence of sodium acetate yielded the corresponding S-alkylated derivatives ( 2a-e ). The latter compounds underwent cyclization into thienopyrimidines ( 4a-e ) upon treatment with sodium ethoxide in ethanol. The reaction of ( 4a ) with hydrazine hydrate led to the formation of 5-amino-4-methyl-2-phenylthieno[2,3-d]pyrimidine-2-carbohydrazide ( 5 ). Compound ( 5 ) was reacted with a variety of reagents to produce other new thienopyrimidines as well as oxadiazolylthienopyrimidines ( 6, 11 ).