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61.
Ahmed Hanan A. Moussa Bahia A. El-Bagary Ramzia I. Darwish Mahmoud N. 《平面色谱法杂志一现代薄层色谱法》2013,26(1):56-61
JPC – Journal of Planar Chromatography – Modern TLC - Three selective, precise, and accurate methods were developed and validated for the simultaneous determination of ofloxacin and... 相似文献
62.
We report here the synthesis of a nanopolymer-supported palladium(II) complex catalyst, [PS-tet-Pd(II)] using a simple protocol. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR, and energy dispersive X-ray spectroscopy (EDS). PS-tet-Pd(II) proves to be a useful heterogeneous catalyst in the copper- and phosphine-free Sonogashira coupling reaction in water. The catalyst can be recovered from the reaction mixture by simple filtration and reused several times without any significant loss of catalytic activity. 相似文献
63.
Michel E. Marhic Peter A. Andrekson Periklis Petropoulos Stojan Radic Christophe Peucheret Mahmoud Jazayerifar 《Laser \u0026amp; Photonics Reviews》2015,9(1):50-74
The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase‐insensitive amplifiers (PIAs) and phase‐sensitive amplifiers (PSAs) are considered. Low‐penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength‐ and time‐division multiplexed formats. High‐quality mid‐span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All‐optical amplitude regeneration of amplitude‐modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase‐modulated signals. A PSA with 1.1‐dB noise figure has been demonstrated, and preliminary wavelength‐division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength‐division multiplexed long‐haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long‐haul communication networks are discussed.
64.
Prof. Dr. Samih A. Halawy Dr. Ahmed I. Osman Dr. Adel Abdelkader Mahmoud Nasr Prof. Dr. David W. Rooney 《ChemistryOpen》2022,11(3):e202200021
Measuring the Lewis-acidic surface sites in catalysis is problematic when the material‘s surface area is very low (SBET ≤1 m2 ⋅ g−1). For the first time, a quantitative assessment of total acidic surface sites of very small surface area catalysts (MoO3 as pure and mixed with 5–30 % CdO (wt/wt), as well as CdO for comparison) was performed using a smart new probe molecule, tetrahydrofuran (THF). The results were nearly identical compared to using another commonly used probe molecule, pyridine. This audition is based on the limited values of the surface area of these samples that likely require a relatively moderate basic molecule as THF with pKb=16.08, rather than strong basic molecules such as NH3 (pKb=4.75) or pyridine (pKb=8.77). We propose mechanisms for the interaction of vapour phase molecules of THF with the Lewis-cationic Mo and Cd atoms of these catalysts. Besides, dehydration of isopropyl alcohol was used as a probe reaction to investigate the catalytic activity of these catalysts to further support our findings in the case of THF in a temperature range of 175–300 °C. A good agreement between the obtained data of sample MoO3-10 % CdO, which is characterised by the highest surface area value, the population of Lewis-acidic sites and % selectivity of propylene at all the applied reaction temperatures was found. 相似文献
65.
Saleh S. Alarfaji Ismat H. Ali Mutasem Z. Bani-Fwaz Mahmoud A. Bedair 《Molecules (Basel, Switzerland)》2021,26(11)
Despite the extensive use of carbon steel in all industrial sectors, particularly in the petroleum industry, its low corrosion resistance is an ongoing problem for these industries. In the current work, two malonyl dihydrazide derivatives, namely 2,2’-malonylbis (N-phenylhydrazine-1-carbothiamide (MBC) and N’1, N’3-bis(-2-hydroxybenzylidene) malonohydrazide (HBM), were examined as inhibitors for the carbon steel corrosion in 1.0 M HCl. Both MBC and HBM were characterised using thin-layer chromatography, elemental analysis, infrared spectroscopy, and nuclear magnetic resonance techniques. The corrosion tests were performed using mass loss measurements, polarisation curves, and electrochemical impedance spectroscopy. It is obtained from the mass loss studies that the optimal concentration for both inhibitors is 2.0 × 10−5 mol/L, and the inhibition efficiencies reached up to 90.7% and 84.5% for MBC and HBM, respectively. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) indicate an increased impedance in the presence of both MBC and HBM and mixed-type inhibitors, respectively. Both inhibitors can mitigate corrosion in the range of 298–328 K. Values of free energy changes obtained from the Langmuir model suggest that the inhibitors suppress the corrosion process principally by chemisorption. The computational investigations were conducted to identify the factors connected with the anti-corrosive properties of the examined inhibitors. 相似文献
66.
Mahmoud Emam Doaa R. Abdel-Haleem Maha M. Salem Lina Jamil M. Abdel-Hafez Rasha R. Abdel Latif Shaimaa Mahmoud Farag Mansour Sobeh Mohamed A. El Raey 《Molecules (Basel, Switzerland)》2021,26(6)
Infections associated with the emergence of multidrug resistance and mosquito-borne diseases have resulted in serious crises associated with high mortality and left behind a huge socioeconomic burden. The chemical investigation of Lavandula coronopifolia aerial parts extract using HPLC–MS/MS led to the tentative identification of 46 compounds belonging to phenolic acids, flavonoids and their glycosides, and biflavonoids. The extract displayed larvicidal activity against Culex pipiens larvae (LC50 = 29.08 µg/mL at 72 h). It significantly inhibited cytochrome P-450 monooxygenase (CYP450), acetylcholinesterase (AChE), and carboxylesterase (CarE) enzymes with the comparable pattern to the control group, which could explain the mode of larvae toxification. The extract also inhibited the biofilm formation of Pseudomonas aeruginosa by 17–38% at different Minimum Inhibitory Concentrations (MICs) (0.5–0.125 mg/mL) while the activity was doubled when combined with ciprofloxacin (ratio = 1:1 v:v). In conclusion, the wild plant, L. coronopifolia, can be considered a promising natural source against resistant bacteria and infectious carriers. 相似文献
67.
Youssef Rasha M. Khamis Essam F. El-Sayed Mahmoud A. Abdel Moneim Mona M. 《平面色谱法杂志一现代薄层色谱法》2014,27(1):58-65
JPC – Journal of Planar Chromatography – Modern TLC - A highly validated and selective high-performance thin-layer chromatography (HPTLC) method was developed for the determination of... 相似文献
68.
The relationship between the rheological properties of nylon-6,6 solutions and the morphology of their electrospun nanofibers was established. The viscosity of nylon-6,6 in formic acid(90%) was measured in the concentration range of 5 wt%-25 wt% using a programmable viscometer. Electrospinning of nylon-6,6 solutions was carried out under controlled parameters. The chemical structure, morphology and thermal properties of the obtained nanofibers were investigated using Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM) and differential scanning calorimetry(DSC), respectively. Entanglement concentration(ce) was found to be 15 wt% and a power law relationship between specific viscosity and solution concentration was observed with exponents of 2.0 and 3.3 for semi-dilute unentangled(c ce) and semi-dilute entangled(c ce) regimes, respectively. The diameter and uniformity of the nanofibers were found to be dependent on the viscosity. Moreover, the average diameter of electrospun nanofibers was found to be dependent on zero shear rate viscosity and normalized concentration(c/ce) in a power law relationship with exponents of 0.298 and 0.816, respectively. For nylon-6,6 solutions, the entanglement concentration(ce = 15 wt%) provides the threshold viscosity required for the formation of a stable polymeric jet during electrospinning and producing uniform beadless fibers. For concentrations less than ce, beaded fibers with some irregularities are formed. DSC analysis showed an increase in crystallinity of all electrospun samples compared to original polymer. Furthermore, Based on FTIR spectroscopy, α phase is dominant in electrospun nanofibers and minor amount of β and γ phases is also available. 相似文献
69.
Various fused-heterocyclic-derivatives containing thiazolopyridine moieties has been synthesized by allowing 5-aminothiazolo[3,2-a]pyridine derivative 1 to undergo annulations reactions with different reagents under different-reaction conditions. The biological assessment of compounds 2 , 11 , 14 , 15 , and 19 showed remarkable antimicrobial activities. In addition, selected derivatives of the products were screened for their anticancer activities against two tumor cell lines using MTT assay and the results showed that some of these compounds have potent cytotoxic effect, as concluded from their IC50 values. Meanwhile, compounds 3a , 7 have exhibited very strong potency as anticancer candidates. Thiazolopyridine structures have been confirmed as a useful lead compounds for the development of new anticancer agents. Molecular docking showed that,-some of the synthesized compounds more suitable inhibitor against-ALR2 with farther alteration in future. 相似文献
70.
The chalcone as (E)-1-([1,1′-biphenyl]-4-yl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one ( 3 ) was reacted with various active methylene compounds via Michael addition reaction under different conditions. In one hand, chalcone 3 reacted with isatin and glycine in one pot reaction via 1,3-dipolar cycloaddition reaction. On the other hand, chalcone 3 was also reacted with different N-nucleophiles via direct addition on the carbonyl group to award cyclic and/or acyclic products. Meanwhile, the reaction of chalcone 3 with S-benzylthiuronium chloride afforded the thio-Michael addition product. Chalcone 3 and 10 novel synthesized compounds were screened against two cell lines (HepG2 and MCF-7). Among of them, thiosemicarbazone 16 , oxime 14 and pyrimidine-2(1H)-thione 19 derivatives revealed an excellent activity against both cell lines (IC50 values = 6.79-12.91 μM), whereas thiosemicarbazone 16 (6.79 ± 0.5 and 7.58 ± 0.6 μM) showed the highest activity. 相似文献