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71.
Hassan A. M. Hendawy Hisham E. Abdellatef Wafaa S. Hassan Abdul Monem O. K. Abu Shagor 《Journal of the Iranian Chemical Society》2018,15(8):1881-1888
In this article, we report a methodology for the voltammetric behavior of meclizine hydrochloride at different nano modified electrodes e.g., Glassy carbon (GCE), pencil graphite (PGE), Carbon Nano tubes-carbon paste (CNTS-CPE) and Carbon Nano tubes-zinc oxide carbon paste (CNTS/ZnO-CPE) using cyclic and square wave voltammetry and the highest performance of them was CPE/CNTs/ZnO electrode and therefore was used as working electrode. The oxidation reaction mechanism of meclizine hydrochloride (MEC-HCL) is proposed to be one electron system. The results obtained with a square wave were linear over the concentration ranges 19.5–102.4 ng mL?1 with a correlation coefficient 0.998. The square wave technique showed a low of detectable (LOD) of 6.444 ng/mL and a limit of quantification (LOQ) of 19.530 ng/mL at CNTS/ZnO-CPE. Based on these findings, a simple and not time-consuming method was used for the analysis of MEC-HCL in pharmaceutics and biological fluids. The method showed a minimum detectability (LOD) of 0.02, 0.008 and 0.14 lg/mL and a limit of quantitation (LOQ) of 0.06, 0.02 and 0.42 lg/mL at PGE, CPE and GCE, respectively. The method was validated and compared with the reference valid method. It revealed good accuracy and reproducible results. The anticipated voltammetric procedure has the advantage of being simple, precise, inexpensive and highly sensitive. 相似文献
72.
Hisham Sati 《Nuclear Physics B》2011,853(3):739-759
We interpret heterotic M-theory in terms of h-cobordism, that is the eleven-manifold is a product of the ten-manifold times an interval is translated into a statement that the former is a cobordism of the latter which is a homotopy equivalence. In the non-simply connected case, which is important for model building, the interpretation is then in terms of s-cobordism, so that the cobordism is a simple-homotopy equivalence. This gives constraints on the possible cobordisms depending on the fundamental groups and hence provides a characterization of possible compactification manifolds using the Whitehead group - a quotient of algebraic K-theory of the integral group ring of the fundamental group - and a distinguished element, the Whitehead torsion. We also consider the effect on the dynamics via diffeomorphisms and general dimensional reduction, and comment on the effect on F-theory compactifications. 相似文献
73.
Paul D. Robinson Hisham G. Lutfi Yuqing Hou Cal Y. Meyers 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):582-584
The preparation of sp‐9‐acetylfluorene from the reaction of 9‐fluorenyllithium with acetyl chloride also provided 9‐(1‐acetoxyethylidene)fluorene (`diacetylfluorene') and 1,1‐di(9‐fluorenyl)ethanol, (II), as by‐products recently characterized by X‐ray analysis. A third by‐product, 1,1‐di(9‐fluorenyl)ethyl acetate, (III), C30H24O2, has now been unequivocally identified for the first time, and emanates from the acetylation of the oxyanion of (II). In the asymmetric unit, compound (III) exists as two almost identical structures which differ slightly, but significantly, in conformation. Neither possesses the significant fluorene‐ring bowing or the perpendicularity of the two ring planes exhibited by (II). The angle between the least‐squares planes of the two fluorene rings of (III) is 58.45 (9) and 60.95 (10)°, respectively, for the two conformations, and their corresponding bonding parameters also differ slightly in a number of instances. 相似文献
74.
Mohy S. Mansour Hisham Imam Khaled A. Elsayed Wafaa Abbass 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009,64(10):1079
One of the most recently applied laser-based techniques in combustion environment is the laser-induced breakdown spectroscopy (LIBS). The technique has been extensively and successfully applied to elemental concentration measurements in solids and liquids. The LIBS signal is much weaker in gases and hence more work is required for quantitative measurements in flames. In the present work we used two orthogonal Nd:YAG lasers that operate at the fundamental wavelength with laser pulse energy of about 100 mJ/pulse. A Princeton-Instruments IMAX ICCD camera attached to a PI-Echelle spectrometer was used for signal detection. The lasers are focused using two 5-cm lenses. Several calibration points have been collected in well defined and homogeneous mixtures of air and fuel in order to be used as references for the measurements in turbulent partially premixed flames. This work shows that the application of the LIBS technique in a turbulent combustion environment is feasible and signal is enhanced by applying an orthogonal dual-pulse arrangement for air–fuel. 相似文献
75.
A method is described for extraction and quantification of celecoxib in tablets. The extraction was achieved through centrifugation of the fine powder of the tablets in Acetonitrile (ACN). The extract was examined by LC. The chromatographic separation was carried out on a Caltrex AIII column, a relatively new packing material consisting of silica-bonded calix[8]arene, using isocratic binary mobile phase of ACN and H2O (55%:45%, v/v). A diode array detector was used at 254 nm for detection. The method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. The limits of detection and quantitation were 0.122 and 0.488 μg mL?1, respectively. The recovery value of this method was 101.88% and the reproducibility was within 2.08. 相似文献
76.
Hisham Abdel-Aziz Hashem 《Chromatographia》2010,71(1-2):31-35
A simple, rapid and accurate, routine-LC method is described for simultaneous determination of paracetamol, caffeine and acetylsalicylic acid in a tablet formulation. This study represents a new application for the calixarene stationary phases. The chromatographic separation of the three pharmaceuticals was achieved on a Caltrex BIIE column (250 × 4 mm, 5 μm) using a binary mobile phase of 14% ACN and 86% 50 mM NaH2PO4 pH 3.0 at 1 mL min?1 flow rate. Detection was at 214 nm. Separation was achieved in less than 15 min. The method was validated for system efficiency, linearity, accuracy, precision, limit of detection and quantification, specificity, stability and robustness. The limits of detection were 4.88, 9.77 and 78.13 ng per 10 μL of their injected volumes, respectively. The recovery values of this method were between 94.63 and 101.85 and the reproducibility was within 3.88. The method could also be used for separation and determination of salicylic acid which is considered the most important degradation product of acetylsalicylic acid. 相似文献
77.
Hisham M. Aly 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(3):437-440
Column chromatographic technique has been utilized to study the column performance of uranyl ion separation on tin(IV) antimonite hydrous oxide matrix. Different flow rates were applied, at 0.6 ionic strength and pH 3, to evaluate the effect of different flow rate on column breakthrough behaviour. Van Demeeter equation was used to emphasize the optimum column conditions. High equivalent to theoretical plate, breakthrough capacity (Q 0.5) were also calculated. 相似文献
78.
Poly(terephthalamide) microcapsules can be reproducibly and easily prepared by interfacial polycondensation around emulsion
droplets in water. Oil drops of cyclohexane/chloroform mixture stabilized with poly(vinyl alcohol) containing terephthaloylchloride
serve as soft template. The interfacial polycondensation starts immediately after addition of an amine mixture (hexamethylenediamine/diethylenetriamine).
Light and scanning electron microscopy prove the formation of capsules with size distribution in the range from a few up to
100 μm depending on particular composition of the reaction mixture. The morphology of the capsule wall is characterized by
precipitated particles. If instead of pure organic solvents a reactive oil phase is used as template, the capsules can serve
in subsequent reactions as templates for the synthesis of composite particles. In this way, styrene can be radically polymerized
inside the capsule leading to composite capsules. The capsule morphology is determined by the partition of all components
between all phases. 相似文献
79.
Electric power frameworks become intensely loaded because of the expanded power demand, and as a result, the power system faces great power losses and fault currents. The integration of Distribution Generation (DG) units plays a key role in minimizing the load pressure on a power system. DGs are transmitted with a high fault current, which surpasses the evaluations of circuit breakers. This paper presents various DG units’ optimal placement with Fault Current Limiters (FCLs) in different phases. The Improved Coyote Optimize Algorithm (ICOA) and Electrical Transient Analyzer Program (ETAP) are assessed for the proposed technique in terms of normal and faulty working status. Similarly, to enhance the efficiency of a distribution system, a fuzzy-based multi-objective mechanism is applied. The proposed method is employed on an IEEE 21-bus and 28-bus distribution system. The simulation analysis proved that the power losses and fault levels are reduced at an acceptable level. 相似文献
80.
Yuqing Hou Paul D. Robinson Hisham G. Lutfi Cal Y. Meyers 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):428-430
Treatment of 9‐fluorenyllithium with acetyl chloride produces 9‐acetylfluorene, (I), and several by‐products, among which is `diacetylfluorene', now characterized definitively as 9‐(1‐acetoxyethylidene)fluorene [IUPAC name: (1‐fluoren‐9‐ylidene)ethyl acetate], (II), C17H14O2, derived from acetylation of initially formed (I). Various parameters disclose substantial structural distortion within (II) emanating from A(1,3) strain associated with the 9‐(acetoxyethylidenyl)fluorene system. 相似文献