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31.
Mohamed E. Mahmoud Sawsan S. Haggag M. Abdel Rafea Tarek M. Abdel-Fattah 《Polyhedron》2009,28(16):3407-3414
An extensive study was performed and reported for evaluation and optimization of the factors affecting thin film formation of nano-sized Co(II)-8-hydroxyquinolate complex by surface layer-by-layer chemical deposition method. The formation of uniform thin films of nano-crystalline metal complex is heavily dependent on several important factors. Variation in metal and ligand concentrations (1:1–1:3) was found to show insignificant contribution to the molar stoichiometric ratio of the synthesized thin film of nano-sized Co(II)-8-hydroxyquinolate. The number of dipping cycles (2–50) was characterized by strong influence on the thin film thickness. The dependence of the immersion time (2–50 s) was proved to influence the crystal growth and homogeneity of the thin film. The role of pH of metal and ligand solutions was identified by strong contribution in development and formation of deposited Co(II)-8-hydroxyquinolate complex thin film. Finally, the role of solvent on the thin film formation was also studied and evaluated. Metal analysis, SEM, EI-MS, FT-IR and TGA were applied as monitoring techniques of these factors. The optical properties of Co(II)-8-hydroxyquinolate complex were also studied and the complex thin films were characterized by the highest optical transition from π–π* or n, π* states with energy gap in the UV-range at 3.13 eV. The lowest optical transition resulted from d–d transition or metal centered transition with energy 1.5 eV while, the optical transition at 2.35 eV is the contribution of metal ligand or ligand metal transition. In the light of the optical measurement, Co(II)-8-hydroxyquinolate complex can be considered as an organic semiconductor with the potential applications in the design of organic light-emitting diodes (OLEMs). 相似文献
32.
Lamyae El Gonnouni Tarek El Bardouni Mariam Zoubair Mohamed Idaomar Abderrahmane Senhoo 《原子核物理评论》2011,28(2):236-240
In this paper, we have addressed the problem of the radiation transport with the Monte Carlo N particle(MCNP) code. This is a general purpose Monte Carlo tool designed to transport neutron, photon and electron in three dimensional geometries. To examine the performance of MCNP5 code in the field of external radiotherapy, we performed the modeling of an Electron Density phantom (EDP) irradiated by photons from 60Co source. The model was used to calculate the Percent Depth Dose (PDD) at different depths in an EDP. One field size for PDD has been examined. A 60Co photons source placed at 80 cm source to surface distance (SSD). The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat. 相似文献
33.
Tarek S. Mansour 《合成通讯》2013,43(3-4):659-665
Nitrogen protected amino acid imidazolides undergo facile carbon acylation with magnesium p-nitrobenzylmalonate dihydrate in THF to give pseudodipeptides in 30-79% isolated yield. 相似文献
34.
Mónica C. Gonzalez Tarek M. Hashem Laurent Jakob André M. Braum 《Fresenius' Journal of Analytical Chemistry》1995,351(1):92-97
The oxidative degradation of 3-amino 5-methyl isoxazole initiated by the VUV photolysis of water at 172 nm has been studied. Mineralization of CO2, H2O, NO
3
–
and NH
4
+
is more efficient when reductive conditions (argon saturated solutions) are favoured. Formation of compounds which cannot be completely oxidised to CO2 is observed. Experiments performed under strictly oxidative conditions show higher yields of these inert compounds and, hence, incomplete mineralization. Cyanide was formed in concentrations lower than 5×10–5 mol/l. In alkaline aqueous solutions, cyanide is completely transformed into CO
3
2–
, NH
4
+
and NO
3
–
during the irradiation time needed to mineralize the isoxazole. Therefore, cyanide does not present a potential risk for the use of the VUV photolysis for isoxazole degradation. Similarly, organic nitrogen is converted into both, NO
3
–
and NH
4
+
. The relative concentrations of the two ions depend on total irradiation time, oxygen saturation and reactor geometry. A sequence of reactions is proposed and discussed.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday 相似文献
35.
Ali M. Ali Ayman H. Ahmed Tarek A. Mohamed Bassem H. Mohamed 《Transition Metal Chemistry》2007,32(4):461-467
New copper(II), nickel(II), iron(III) and palladium(II) Schiff base complexes derived from o-tolidine and selected aldehydes, namely salicyaldehyde and 2-hydroxynaphthaldehyde have been synthesized and characterized
by a combination of elemental analyses, magnetic moments, spectral (u.v.–vis., i.r.) and thermal (tg, dtg) mesurements. The
corrosion inhibition of aluminium and copper in 1 M HCl and chromium–nickel steel in crude oil using N,N′bis(salicyledene)-o-tolidine have been studied by weight loss method. 相似文献
36.
Although, the effects of ultrasonic irradiation on multiphase flow through porous media have been studied in the past few
decades, the physics of the acoustic interaction between fluid and rock is not yet well understood. Various mechanisms may
be responsible for enhancing the flow of oil through porous media in the presence of an acoustic field. Capillary related
mechanisms are peristaltic transport due to mechanical deformation of the pore walls, reduction of capillary forces due to
the destruction of surface films generated across pore boundaries, coalescence of oil drops due to Bjerknes forces, oscillation
and excitation of capillary trapped oil drops, forces generated by cavitating bubbles, and sonocapillary effects. Insight
into the physical principles governing the mobilization of oil by ultrasonic waves is vital for developing and implementing
novel techniques of oil extraction. This paper aims at identifying and analyzing the influence of high-frequency, high-intensity
ultrasonic radiation on capillary imbibition. Laboratory experiments were performed using cylindrical Berea sandstone and
Indiana limestone samples with all sides (quasi-co-current imbibition), and only one side (counter-current imbibition) contacting
with the aqueous phase. The oil saturated cores were placed in an ultrasonic bath, and brought into contact with the aqueous
phase. The recovery rate due to capillary imbibition was monitored against time. Air–water, mineral oil–brine, mineral oil–surfactant
solution and mineral oil-polymer solution experiments were run each exploring a separate physical process governing acoustic
stimulation. Water–air imbibition tests isolate the effect of ultrasound on wettability, capillarity and density, while oil–brine
imbibition experiments help outline the ultrasonic effect on viscosity and interfacial interaction between oil, rock and aqueous
phase. We find that ultrasonic irradiation enhances capillary imbibition recovery of oil for various fluid pairs, and that
such process is dependent on the interfacial tension and density of the fluids. Although more evidence is needed, some runs
hint that wettability was not altered substantially under ultrasound. Preliminary analysis of the imbibition recoveries also
suggests that ultrasound enhances surfactant solubility and reduce surfactant adsorption onto the rock matrix. Additionally,
counter-current experiments involving kerosene and brine in epoxy coated Berea sandstone showed a dramatic decline in recovery.
Therefore, the effectiveness of any ultrasonic application may strongly depend on the nature of interaction type, i.e., co-
or counter-current flow. A modified form of an exponential model was employed to fit the recovery curves in an attempt to
quantify the factors causing the incremental recovery by ultrasonic waves for different fluid pairs and rock types. 相似文献
37.
Several new pyridine derivatives were prepared via reaction of enaminoketones 1a , 1b , 1c , 1d with active hydrogen reagents. Reaction of the enaminoketones 1a , 1b , 1c with 4‐acetyl‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one 2a yielded the pyridines 3a , 3b , 3c . Condensation of the enaminonitrile 1d with compounds 2b , 2c , 2d and compound 8 gave the pyridine derivatives 6a , 6b , 6c and 10 respectively. Also, (3‐(dimethylamino)acryloyl)‐2H‐chromen‐2‐one 1a reacted with active methylenes in diethyl 3‐oxopentanedioate 12 and 4‐methyl‐6‐oxo‐2‐thioxo‐1,2,5,6‐tetrahydropyridine‐3‐carbonitrile 15 to afford the pyridine derivatives 14 and 16 respectively. 相似文献
38.
Peter?ConstantinEmail authorView authors OrcID profile Tarek?Elgindi Mihaela?Ignatova Vlad?Vicol 《Journal of Nonlinear Science》2017,27(1):197-211
We consider a model of electroconvection motivated by studies of the motion of a two-dimensional annular suspended smectic film under the influence of an electric potential maintained at the boundary by two electrodes. We prove that this electroconvection model has global in time unique smooth solutions. 相似文献
39.
A simple, rapid, and selective HPLC-diode array detector method was developed for the simultaneous determination of lidocaine hydrochloride (LD) and cetylpyridinium chloride (CPC) in two combined pharmaceutical formulations. Effective chromatographic separation was achieved on a Zorbax SB-C8 (4.6 x 250 mm, 5 microm particle size) column with gradient elution using a mobile phase composed of 0.05 M phosphoric acid and acetonitrile. The gradient elution started with 25% (v/v) acetonitrile, ramped up linearly to 85% in 5 min, and then was constant until the end of the run. The mobile phase was pumped at a flow rate of 1.2 mL/min. The multiple wavelength detector was set at 214 and 258 nm, and quantification of the analytes was based on measuring their peak areas. The retention times for LD and CPC were about 3.4 and 7.3 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to linearity, range, precision, accuracy, selectivity, robustness, LOD, and LOQ. Calibration curves were linear in the range of 5-200 and 10-400 microg/mL for LD and CPC, respectively, with correlation coefficients > 0.999. The proposed method was proven to be stability-indicating by the resolution of the two analytes from the related substance and potential impurity (2,6-dimethylaniline) as well as from forced-degradation products. The validated HPLC method was extended to the analysis of LD and CPC in two combined oral gel preparations for which the two analytes were successfully resolved from the pharmaceutical adjuvants and quantified with recoveries not less than 97.9%. 相似文献
40.
Tarek Sayed Ahmed 《Mathematical Logic Quarterly》2011,57(4):384-394
Using games, as introduced by Hirsch and Hodkinson in algebraic logic, we give a recursive axiomatization of the class RQPEA α of representable quasi‐polyadic equality algebras of any dimension α. Following Sain and Thompson in modifying Andréka’s methods of splitting, to adapt the quasi‐polyadic equality case, we show that if Σ is a set of equations axiomatizing RPEA n for $2< n <\omegaUsing games, as introduced by Hirsch and Hodkinson in algebraic logic, we give a recursive axiomatization of the class RQPEA α of representable quasi‐polyadic equality algebras of any dimension α. Following Sain and Thompson in modifying Andréka’s methods of splitting, to adapt the quasi‐polyadic equality case, we show that if Σ is a set of equations axiomatizing RPEA n for $2< n <\omega$ and $l< n,$ $k < n$, k′ < ω are natural numbers, then Σ contains infinitely equations in which ? occurs, one of + or · occurs, a diagonal or a permutation with index l occurs, more than k cylindrifications and more than k′ variables occur. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献