This paper integrates a Real Power Differential Scheme (RPDS) for power transformer protection. The suggested RPDS for power transformer computes the active power loci during normal operation, switching, normal, and internal, involves turn to turn, and external faults at varied load angles. The proposed RPDS concept is based on monitoring and comparing the transformers primary and secondary active and reactive powers. The dynamic response of the proposed RPDS is tested 300 MVA, 220/66 kV, Y/Δ transformer. Furthermore, the suggested scheme is simulated with the use of Matlab/Simulink then tested for various fault and switching conditions. Moreover, the RPDS is checked for inter turn fault conditions at primary and secondary sides. The evaluation of the suggested scheme confirms the superiority of the proposed scheme to distinguish internal and external faults as well as magnetizing inrush currents with good selectivity, high speed, sensitivity, stability limits and high accuracy response of the power differential scheme. Finally, the suggested scheme is able to detect correctly the turn to turn faults for wide range of fault resistances but fails at very low values.
Authors:M. Barakat, A. Al-Doss, A. Elshafei, K. Moustafa and E. Ahmed
The objective of this study was to develop a simple anther culture protocol for a range of Saudi wheat genotypes. Seven wheat genotypes were evaluated in anther culture on five different medium protocols for their ability to initiate callus and green plants. The estimates of significance for the effects of genotypes, and medium protocols used, and their interactions on callus induction, callus weight and shoot formation derived from anther explants indicated that the in vitro traits were significantly influenced by the genotypes, medium protocols, and their interactions. The percentage of explants that developed calli ranged from 0.41% (Lang) to 15.39% (Irena) averaged across the five medium protocols with an average 4.45%. The genotype Irena produced the highest average means of shoot formation (69.65%) across medium protocols. The genotype Yecora Rojo (13.73%) was significantly inferior to all other tested genotypes for shoot formation.
Authors:R. Itawi, S. Al-Jobori, M. Jalil, S. Farhan, A. Mheemeed, Kh. Saaeed and E. Ahmed
Eleven food colouring substances are analyzed for their elemental content by the method of instrumental neutron activation analysis, and the concentrations of fourteen elements present in these samples are presented.
Authors:R. Itawi, S. Al-Jobori, M. Jalil, S. Farhan, A. Mheemeed, Kh. Saaeed and E. Ahmed
Thirteen textile dyes have been analyzed by the method of insturmental neutron activation analysis for their components of major and trace elements, and the concentration of thirteen elements in these samples are presented.
Authors:Fawad Javed, Hameeda Bashir Ahmed, Roberto Crespi and Georgios E. Romanos
A secure implant primary (mechanical) stability is positively associated with a successful implant integration and long-term successful clinical outcome. Therefore, it is essential to assess the initial stability at different time-points to ensure a successful osseointegration. The present study critically reviews the factors that may play a role in achieving a successful initial stability in dental implants. Databases were searched from 1983 up to and including October 2013 using different combinations of various keywords. Bone quality and quantity, implant geometry, and surgical technique adopted may significantly influence primary stability and overall success rate of dental implants.
Authors:Dustin M. Clifford, Ahmed A. El-Gendy, Amos J. Lu, Dmitry Pestov and Everett E. Carpenter
Cobalt nanoparticles were synthesized using continuous-flow (CF) chemistry in a stainless steel microreactor for the first time at high output based on the ethanol hydrazine alkaline system (EHAS) producing a yield as high as 1 g per hour [1, 2]. Continuous-flow (CF) synthetic chemistry provides uninterrupted product formation allowing for advantages including decreased preparation time, improved product quality, and greater efficiency. This successful synthetic framework in continuous-flow of magnetic Co nanoparticles indicates feasibility for scaled-up production. The average particle size by transmission electron microscopy (TEM) of the as-synthesized cobalt was 30±10 nm, average crystallite size by Scherrer analysis (fcc phase) was 15±2 nm, and the estimated magnetic core size was 6±1 nm. Elemental surface analysis (X-ray photoelectron spectroscopy [XPS]) indicates a thin CoO surface layer. As-synthesized cobalt nanoparticles possessed a saturation magnetization (Ms) of 125±1 emu/g and coercivity (Hc) of 120±5 Oe. The actual Ms is expected to be greater since the as-synthesized cobalt mass was not weight-corrected (nonmagnetic mass: reaction by-products, solvent, etc.). Our novel high-output, continuous-flow production (>1 g/hr) of highly magnetic cobalt nanoparticles opens an avenue toward industrial-scale production of several other single element magnetic nanomaterials.
Authors:Michael E. El-Kommos, Niveen A. Mohamed, Hassan R.H. Ali and Ahmed F. Abdel Hakiem
A new spectrodensitometric method was developed for the simultaneous determination of a quaternary mixture of antihyperlipidemics containing niacin, atorvastatin, and bezafibrate with either ezetimibe or simvastatin. Densitometric analysis was carried out using high-performance thin-layer chromatographic (HPTLC) silica gel 60G F254 plates as the stationary phase. The plates were developed with benzene—ACN—n-butanol (7:2:1, v/v) + 1.50%, v/v, glacial HOAC in absorbance mode at 242 nm. The retention factors of niacin, atorvastatin, bezafibrate, ezetimibe, and simvastatin were 0.17, 0.38, 0.51, 0.65, and 0.66, respectively. The method was validated according to the United States Pharmacopeia and National Formulary (USP 31—NF 26) and the International Conference on Harmonization (ICH) guidelines. Linearity ranges of all studied drugs were found to be in the range of 15–650 ng band−1 with correlation coefficient values of 0.9975 or more. Limits of detection and quantitation were 5–50 and 15–150 ng band−1, respectively. Upon applying polynomial regression to the same concentration ranges of standard solutions of all investigated drugs as well as spiked bezafibrate samples to rabbit plasma, correlation coefficient values had greatly improved. The proposed method was successfully applied for the simultaneous determination of the studied antihyperlipidemic drugs in plasma and in their pharmaceutical formulations. The developed method was utilized to study the pharmacokinetic behavior of bezafibrate and its drug—drug interaction with atorvastatin in rabbit males. This study has proven the increased myotoxicity risk upon coadministration of atorvastatin with bezafibrate.
Authors:Aziz Ahmed, Sayeed Ahmad, Mahfooz Ur-Rahman, Tamboli E. Tajuddin, Ranbir Verma, Mohd Afzal and Prahlad Singh Mehra
Bacoside A, a triterpenoid saponin, is a major constituent isolated from Bacopa monnieri (L.) Wettst. (Scrophulariaceae), used as a memory enhancer. Bacoside A and B are active ingredients in Bacopa herb and have antioxidant and hepatoprotective activities
A new rapid, simple, and economical high-performance thin-layer chromatographic (HPTLC) method was developed and validated for densitometric quantitative analysis of bacoside A in powdered leaves from different geographical regions of India.
Materials and methods
An amount of 10 mg mL−1 methanol extract of powdered leaves from different geographic regions was used for sample application on precoated silica gel 60 F254 aluminum sheets. Standard bacoside A (1 mg mL−1) was used for calibration curve. HPTLC separation was performed on percolated silica gel aluminum plate 60 F254 (20 cm × 10 cm with 0.2 mm thickness) as a stationary phase using ethyl acetate–methanol–water (4:1:1) as the mobile phase. Quantification was achieved by densitometric analysis at 598 nm over the concentration range of 500–4000 ng band−1.
Compact and well-resolved bands for bacoside A from powdered leaves of different geographic regions were found at retardation factor (Rf) 0.53 ± 0.02. The linear regression analysis data for calibration curve showed good linear relationship with regression coefficient r2 = 0.9996 and r2 = 0.99810 with respect to peak area and peak height. The method was validated for precision, recovery, and robustness as per the International Conference on Harmonization (ICH) guidelines. Variation in quantitative analysis of bacoside A in powdered leaves sample from different geographic regions was found by HPTLC method.
Discussion and conclusion
The highest and lowest content of bacoside A in powdered leaves sample from Jammu and Kerala regions, respectively. The variety of B. monnieri in Jammu is superior to other regions of India. The proposed developed HPTLC method can be applied for the quantitative determination of bacoside A in powdered leaves of plant and its formulation.