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91.
A simple, selective and sensitive luminescence method has been developed for the assay of etodolac (I), moxepril HCl (II)
and fexofenadine HCl (III) in bulk drug and pharmaceutical formulations. The method is based on the luminescence sensitization
of europium (Eu3+) by complexation with the studied drugs. The fluorescence intensities of the products were measured at 667 nm for (I) and
at 615 for (II) and (III) while exciting at 276 for all the studied drugs. The fluorescence intensity was directly proportional
to the concentration over the range (20–280), (40–240) and (30–80) ng/ml with limits of detection (LOD) = 0.93, 0.92 and 0.95 μg/ml
for drugs I, II and III respectively. Optimum conditions for the formation of the complex in methanol were carefully studied.
The proposed method was successfully applied for the assay of the studied drugs in pharmaceutical formulations with excellent
recovery. 相似文献
92.
A. A. El‐Khamry S. A. Shiba A. A. Shalaby A. A. Abd alaha 《Journal of heterocyclic chemistry》2006,43(5):1189-1193
The benzoxazinone derivative 2‐(6,8‐dibromo‐4‐oxo‐4H‐benzo[d]‐1,3‐oxazin‐2‐yl)‐3‐(4‐methoxyphenyl) acrylonitrile ( 1 ) has been used as a starting material for preparation of the hitherto unknown pyrazoloquinazolinone and quinazolinone derivatives. Under different conditions the benzoxazinone ( 1 ) was reacted with hydrazine hydrate to provide the pyrazolocarbonitrile derivative ( 2 ) and the azine derivative ( 3 ) and/or the pyrazoloquinazoline derivative ( 4 ). When ( 4 ) was conducted to react either with EAA (ethyl acetoacetate) or Ac2O/AcOH (acetic anhydride/acetic acid) mixture or phthalic anhydride/acetic acid mixture, the pyrazoloquinazoline carbonitrile ( 5 ), pyrazolo‐quinazoline acetic acid ( 6 ) or the pyrazoloquinazolinone derivative ( 7 ) were formed respectively. When ( 1 ) was reacted with phenylhydrazine, a mixture of the quinazolinone derivative ( 8 ) and the hydrazone derivative ( 9 ) were obtained. The benzoxazinone derivative ( 1 ) was found also to react with benzylamine in ethanol or without solvent to give the quinazolinone derivative ( 10 ) or the quinazolindione ( 11 ) respectively. Fusion of ( 1 ) with ammonium acetate yielded the quinazolinone ( 12 ), which was methylated to give ( 13 ) and thiated to the thioxyquinazoline derivative ( 14 ), while reaction of ( 1 ) with formamide gave the N‐formylquinazoline derivative ( 15 ). 相似文献
93.
Kirkman frames having hole type h u m 1 for small h 总被引:1,自引:1,他引:0
We begin an investigation into the spectrum of (non-uniform) Kirkman frames of type h
u
m
1, paying particular attention to the cases where h ∈{2,4,6,8,10,12}. We show that for each of these values of h the obvious necessary conditions on u, m are sufficient in all but at most 24 cases of (h,u,m).
相似文献
94.
Magda N. Shalaby 《先进技术聚合物》2004,15(9):533-538
Sorption behavior of polyoxethylene(n)monooleate series [Ol(EO)n] onto montmorillonite clay was studied at 25°C to investigate the influence of the surfactant's head size on the sorption process. All the tested surfactants exhibited L‐shaped isotherms that means a strong interaction between the adsorbent and the adsorbate. Also, all the obtained isotherms ended with a drastic increase in the isotherm slope at nearly constant equilibrium concentration. This abrupt increase reflected the fairly high affinity of the tested surfactants to the clay surface at high bulk concentration region. The maximum amount adsorbed at the plateau region, Γmax, was calculated according to the Langmuir adsorption theory and followed the order: Ol(EO)14 > Ol(EO)20 < Ol(EO)40 < Ol(EO)80. In case of short ethylene oxide (EO) chain, Γmax decreased with the increase in the chain length; but a reverse result was obtained in case of surfactants with longer EO chain length (20 to 80 units). The free energy of adsorption, ΔG°ad, had negative values indicating the spontaneous adsorption of surfactant molecules onto clay. The values of ΔG°ad increased with increasing EO units from 14 to 20 units and decreased with further elongation in the EO chain from 20 to 80 units. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
95.
M. M. Mohamed Z. F. Ghatass E. A. Shalaby M. M. Kotb M. El-Raey 《Analytical and bioanalytical chemistry》2000,368(8):809-815
A new instrument, which uses a three-phase current to support a double-arc argon plasma torch for evaporation, atomization
and excitation of solid or powder samples, is described. The sampling arc is ignited between the first and second electrode
while the excitation arc is ignited between the second and third electrode. Aerosol generated from the sample (first electrode)
is swept by argon gas, through a hole in the second electrode (carbon tubing electrode), into the excitation plasma. A tangential
stream of argon gas is introduced through an inlet orifice as a coolant gas for the second electrode. This gas stream forces
the excitation arc discharge to rotate reproducibly around the electrode surface. Discharge rotation increases the stability
of the excitation plasma. Spectroscopic measurements are made directly in the current-carrying region of the excitation arc.
An evaluation of each parameter influencing the device performance was performed. Analytical calibration curves were obtained
for Fe, Al, K, and Pb. Finally, the present technique was applied for the analysis of environmental samples. The present method
appears to have significant, low cost analytical utility for environmental measurements.
Received: 7 July 2000 / Revised: 6 September 2000 / Accepted: 10 September 2000 相似文献
96.
Damage of salmon sperm double strand ss dsDNA in solution or immobilized on screen‐printed carbon electrode (SPCE) induced by incubation of DNA with the antineoplastic alkylating agent busulfan (BUS) at various conditions was detected for the first time by simple electrochemical methods. Chemical changes in DNA bases can be detected through the altered electroactivity of the DNA. Electrochemical voltammetric sensing of damage caused by BUS to dsDNA in solution was monitored by the appearance of peaks diagnostic of the oxidation of guanine and adenine. Moreover, crystal violet, which interacts with the DNA immobilized on SPCEs, was used as an effective electroactive indicator, in combination with cyclic voltammetry and differential pulse voltammetry techniques to monitor the cross‐links or damage to DNA. The interaction between BUS and DNA were determined by the changes in the voltammetric peak of crystal violet. The effects of various conditions upon the crystal violet signal were investigated. 相似文献
97.
Hamed E. O. Assy M. G. Shalaby A. M. Sayed R. E. 《Russian Journal of Organic Chemistry》2020,56(11):2005-2013
Russian Journal of Organic Chemistry - The intermolecular cyclization of N-benzyl-2-cyanoacetamide with carbon disulfide followed by intramolecular cyclization gave thioxothiazinone 3. This... 相似文献
98.
99.
Andrew?T.?Jesso David?A.?PikeEmail author Nabil?Shalaby 《Designs, Codes and Cryptography》2011,61(3):345-353
As part of our main result we prove that the blocks of any sufficiently large BIBD(v, 4, λ) can be circularly ordered so that consecutive blocks intersect in exactly one point, i.e., that the 1-block-intersection graphs of such designs are Hamiltonian. In fact, we prove that such graphs are Hamilton-connected. We also consider {1, 2}-block-intersection graphs, in which adjacent vertices have either one or two points in common between their corresponding blocks. These graphs are Hamilton-connected for all sufficiently large BIBD(v, k, λ) with \({k \in \{4,5,6\}}\). 相似文献
100.
B. M. Shalaby V. Kermene D. Pagnoux A. Desfarges-Berthelemot A. Barthélémy 《Applied physics. B, Lasers and optics》2011,105(2):213-217
We report on a fiber laser configuration, emitting two phase-locked and single mode beams at the output of two multicore fibers.
The passive technique is based both on the selective excitation of the only in-phase supermodes of the multicore fibers and
on an intra-cavity angular filtering of the emitted beams to provide phase control. As a proof of principle, we experimentally
demonstrate the coherent combining of the fundamental in-phase supermodes of two parallel 7-cores fibers. 相似文献