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121.
Ching-Min Chang Marian W. Kemblowski Jagath J. Kaluarachchi Alaa Abdin 《Transport in Porous Media》1995,19(3):233-259
Stochastic analysis of steady-state two-phase (water and oil) flow in heterogeneous porous media is performed using the perturbation theory and spectral representation techniques. The governing equations describing the flow are coupled and nonlinear. The key stochastic input variables are intrinsic permeability,k, and the soil and fluid dependent retention parameter, . Three different stochastic combinations of these two imput parameters were considered. The perturbation/spectral analysis was used to develop closed-form expressions that describe stochastic variability of key output processes, such as capillary and individual phase pressures and specific discharges. The analysis also included the estimation of the effective flow properties. The impact of the spatial variability ofk and on the variances of pressures, effective conductivities, and specific discharges was examined. 相似文献
122.
G. A. El-Shobaky A. S. Ahmad M. Mokhtar 《Journal of Radioanalytical and Nuclear Chemistry》1997,219(1):89-94
A copper, zinc and aluminium mixed oxides sample having the nominal composition 0.25 CuO/0.03 ZnO/Al2O3 was prepared by impregnating Al(OH)3 with copper and zinc nitrate solutions, drying at 100 °C then heating in air at 600 °C. The obtained solid was exposed to different doses of -rays (20–160 Mrad). The surface characteristics namelyS
BETVP andr of different treated adsorbents were determined from N2 adsorption isothems measured at –196 °C. The catalytic activity of various irradiated solids was determined by following up the kinetics of CO-oxidation by O2 at 150–200 °C. The results showed that the doses up to 80 Mrad resulted in no significant change in theS
BET but increased slightly theV
P (20%) of the treated adsorbents. The irradiation at 160 Mrad caused an increase of 20% in theS
BET of the irradiated solid sample. The catalytic activity increased progressively by increasing the dose, a dose of 160 Mrad brought about an increase of 140% in the catalyst's activity. The apparent activation energy of the catalytic reaction decreased monotonically by increasing the absorbed dose of -rays which was attributed to a parallel induced decrease in the value of pre-exponential term of the Arrhenius equation. The observed increase in the catalytic activity due to -irradiation has been interpreted as a result of increasing the concentration of catalytically-active sites contributing in chemisorption and catalysis of CO-oxidation via a possible fragmentation of CuO crystallites. 相似文献
123.
Dietrich Dpp Mohsen Abdel-Motaal Gomaa Gerald Henkel Ahmed Mokhtar Nour El-Din 《Journal of heterocyclic chemistry》1995,32(2):603-610
Nucleophilic attack by N2 of N1 N2-diarylformamides 1a-c on C-2 of chloranil (2) and subsequently by N1 on C-1 of 2 initiates the formation of benzimidazolinones 8a-c. In contrast, when 1b-e is reacted with 2,3-dichloro-1,4-naphthoquinone (9) , both chlorine atoms are successively substituted by the two nitrogen atoms and 2-(arylamino)-3-(N-formylarylamino)-1,4-naphthoquinones 13b-e result, which (probably via their cyclic tautomers 12b-e ) may be cyclodehydrogenated to form N1,N3-diarylnaphtho[2,3-d] imidazoline-2,4,9-triones (as 14b,c ). On the other hand, N1,N2diarylacetamidines 15a-d attack 2 and 9 at C-2 with N2 but subsequently exert nucleophilic character at the acetamidine α-carbon attacking C-1 of 2 and 9 , respectively, thus forming 1-aryl-2-(arylimino)-3a-hydroxy-2,3,3a,6-tetrahydro-1N-indol-6-ones 18a-d and 3-aryl-2-(arylimino)-9b-hydroxy-2,3,5,9b-tetrahydro-1-H-benz[e]indol-5-ones 19b,c , respectively. The latter may be thermally dehydrated to the fully conjugated 2,5-dihydro-3H-benz[e]indol-5-ones 20b,c. Unambiguous structural assignments for 18b and 20c are made on the basis of X-ray crystal structure analyses. 相似文献
124.
Noha Fathalla Mokhtar Bishr Abdel Nasser Singab Osama Salama 《Natural product research》2019,33(19):2878-2881
The aim of this work is to characterize the active constituents present in the ethyl acetate fraction of Senna tora, L. Roxb. seeds. Due to the fact that the main biological activity of S. tora, L seeds is attributed to its phenolic compounds which are mainly isolated from Ethyl acetate fraction, to avoid repetition of work and to save time, it was deemed necessary to confirm the identity of these phenolic compounds. This was done by GC-MS and LC-MS analysis of the ethyl acetate fraction where the structures of the isolated compounds were established on the basis of molecular ion peak and their fragmentation pattern. They were identified as Chrysophanol, Chrysarobin, 10-hydroxy-5-methoxy-2-methyl-1, 4-anthracenedione, Rubrofusarin, Parietin, Griseoxanthone-B, Isotorachrysone, and Cumbiasin B.
125.
Ahmed A. Abdel-Khalek Alaa E. D. M. Abdel-Hady Mohamed F. El-Shahat 《Transition Metal Chemistry》1995,20(5):430-434
Summary In aqueous solutions, [Cr(en)3]3+ aquates to [Cr(en)2-(H2O) 2]3+. A kinetic study of the oxidation of [Cr(en)3]3+ by N-bromosuccinimide (NBS) in aqueous solutions and water-alcohol solvent mixtures was performed. The reaction is first order with respect to both total [CrIII] and [NBS]. The rate is inversely dependent upon [H+] in the 7.0–7.9 pH range, and varies with the co-solvent according to the order: MeOH > EtOH > PrOH. An appropriate mechanism, in which the deprotonated [Cr(en)2(OH)(H2O)]2+ is the reactive species, is suggested. Thermodynamic activation parameters have been calculated.Abstracted from the PhD thesis (Ain Shams University) of A. E.- D. M. Abdel-Hady. 相似文献
126.
以二氯-1,3-双(二苯基磷)丙烷基镍(Ⅱ)为催化剂,通过3,6-二氯哒嗪格氏试剂与3,6-二溴-N-戊烷基咔唑共聚得到了一种新型共轭聚合物,并使用IR和1H-NMR等测试手段对单体和聚合物的结构进行了表征。该合成方法所得的共聚物收率为75%,共聚物在N,N-二甲基酰胺(DMF)、二甲基亚砜(DMSO)等极性溶剂和CF3COOH、CH3SO3H、HCOOH等常用有机酸中具有较好的溶解性。用红外(FT-IR)、紫外-可见吸收光谱(UV-vis)、荧光光谱(PL)、X射线衍射、循环伏安(CV)等对聚合物的吸收光谱特性、结晶性和电化学活性进行了探讨。结果表明:聚合物具有较高的发光强度,是一种还原型聚合物,结晶性比较差。 相似文献
127.
Synthesis of imidazo[1,2-b]pyridazines: Fenbendazole,oxifenbendazole analogs and related derivatives
Alaa E. Mourad Dean S. Wise Leroy B. Townsend 《Journal of heterocyclic chemistry》1993,30(5):1365-1372
A series of imidazo[1,2-b]pyridazines has been prepared and evaluated for macrofilaricidal activity against Brugia pahangi or Acanthocheilonema viteae infections in jirds. The imidazo[1,2-b]pyridazine analogs of fen-bendazole and oxifenbendazole are reported. In addition, several 6-aminoimidazo[1,2-b]pyridazine derivatives have been prepared. None of these compounds possessed significant activity against human cytomega-lovirus (HCMV) or filarial infections. 相似文献
128.
A spectrophotometric procedure for the determination of terfenadine and a number of its pharmaceutical preparations has been developed that offers advantages of simplicity, rapidity, sensitivity and stability indication over the official USP (1995) method. The proposed method is based on the formation of ion-pairs by the reaction of terfenadine with some chromotropic acid mono- and bis-azo dyes. Different variables affecting the ion-pair formation were studied and optimized. At the maximum absorption of 557, 521, 592 and 543 nm, Beer's law is obeyed in the range 0.2–18.6, 0.2–16.4, 0.2–25.0 and 0.2–22.2 g ml–1 on using reagents I, II, III and IV, respectively. The stoichiometric ratio and stability of each ion-pair were estimated and the mechanism of the reaction is discussed. The molar absorptivity and Sandell sensitivity of the produced ion-pairs were calculated in addition to Ringbom optimum concentration ranges. Statistical treatment of the experimental results indicates that the procedures are precise and accurate. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedures. The reliability of the methods was established by parallel determination against the official USP method. The procedures described were successfully applied to the determination of the bulk drug and its pharmaceutical formulations by applying the standard addition technique. 相似文献
129.
Laser techniques were applied to an acoustically levitated droplet for remote investigation of the diameter, species concentration and temperature of the suspended droplet. To this end, the third and the fourth harmonic of a Nd:YAG laser were used for investigation of elastic, fluorescence and phosphorescence signals from the droplet. The droplet was seeded with thermographic phosphors and acetone for the phosphorescence and fluorescence measurements, respectively. The techniques were applied simultaneously using an imaging stereoscope. The imaging device allowed for an identical visualization of incoming signal through separate optical filters. Temperature measurements in droplets is important in the study of e.g. exothermic chemical reactions, spray processes, combustion, and in bioanalytical applications where the biological material is temperature sensitive or dependent on optimal temperature for function. Results from these investigations showed that temperature measurements in acoustically levitated droplets using laser-induced phosphorescence are feasible. The results also show the potential of simultaneous laser based measurements on levitated droplets. Diameter variation (surface area), mixture concentration and temperature were measured simultaneously. 相似文献
130.
Ronald G. Sutherland Alaa S. Abd-El-Aziz Adam Pirko Udai S. Gill Choi Chuck Lee 《Journal of heterocyclic chemistry》1988,25(4):1107-1110
An efficient synthesis of 3-mono or 3,4-disubstituted cinnolines from (o-dichlorobenzene)(cyclopentadienyl)iron hexafluorophosphate in three or four steps has been achieved. o-Chlorophenyl-alkyl or alkylaryl ketone complexes obtained from the o-dichlorobenzene complex upon treatment with enolate anions, react with hydrazine forming 3-mono or 3,4-disubstituted 1,4-dihydrocinnoline complexes. Treatment of the later with sodium amide leads to an aromatization-demetallation reaction resulting in formation of cinnolines, i.e. 3-methyl-, 3-phenyl- and 3,4-dimethylcinnoline. The influence of substituents bonded to the carbon atom adjacent to the complexed benzene ring in o-chlorophenyl -alkyl or -alkylaryl ketone prior to cyclization on the cyclization reaction is discussed. 相似文献