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41.
Ahmed Nabih Zaki Rashed 《Journal of Russian Laser Research》2013,34(6):603-613
We present new trends in the performance evaluation of submarine fiber cable system with different ultrahigh multiplexing and propagation techniques over a wide range of the affecting parameters. Our model takes into account the ultimate optical transmission of huge submarine cables with 14,400 channels under different depth conditions. We employ Raman and erbium-doped fiber amplifiers in our study. We investigate the double impact of both temperature and pressure through the defined depth penalty. We also study the soliton transmission technique using two multiplexing methods considered in the design of ultra-wide wavelength division multiplexing (UW-WDM) with 14,400 optical channels and ultra-wide space division multiplexing (UW-SDM) with 440 fiber links. Based on experimental data, both the deep ocean water temperature and pressure are obtained as functions of the water depth. 相似文献
42.
Isothiochromene[3,4‐d] pyrimidine derivatives 2 , 3 , and 4a , b were synthesized from the reaction of 3‐amino‐1‐(pyridin‐4‐yl)‐5‐(pyridin‐4‐ylmethylene)‐5,6,7,8‐tetrahydro‐1H‐isothiochromene‐4‐carbonitrile 1 with acetic anhydride, formamide, urea, or thiourea in appropriate experimental conditions. Combination of 1 with carbon acid derivatives afforded isothiochromene [3,4‐b]pyridine 6 – 8 in good yield. A simple approach for N‐substituted fused isothiochromene derivatives has been explored. A POCl3‐mediated direct amination of isothiochromene amide 2 with NH2‐heterocycles, secondary amines, and carbohydrazides is described and compared with classical method, yielding 10 – 14 . The structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, and spectral data. 相似文献
43.
M. Shaheer Malik Zaki S. Seddigi Shaik Bajee Shaik Azeeza Syed Riyaz Saleh A. Ahmed Ismail I. Althagafi Qazi M. Sajid Jamal Ahmed Kamal 《Journal of Saudi Chemical Society》2019,23(4):503-513
The versatility of multicomponent Biginelli’s reaction is exploited in the development of proline and cyclized cysteine tethered conjugates of monastrol, a kinesin Eg5 inhibitor. Ten new conjugates are synthesized focusing on structural replacement of the ester moiety (C-5 position) of the monastrol backbone with amino acid based amide moieties. On cytotoxic evaluation, conjugate 24 has shown promising in vitro cytotoxic activity against leukemia. Molecular docking studies revealed that the conjugates 19 and 24 exhibit better interaction at kinesin Eg5 receptor compared to monastrol. Moreover, computational calculations and predictions of important molecular properties suggest that these new amino acid based conjugates could be further improved to provide potential anticancer agents. 相似文献
44.
Zaki Nadia G. Mahmoud Walaa H. El Kerdawy Ahmed M. Abdallah Abanoub Mosaad Mohamed Gehad G. 《Research on Chemical Intermediates》2020,46(6):3193-3216
Research on Chemical Intermediates - Reaction of cocaine (Cn) with Ln(III) chloride salts [where Ln?=?La(III), Er(III), and Yb(III)] afforded complexes of the [Ln(Cn)Cl(OH2)3].2Cl type... 相似文献
45.
Agisho Habtamu Abebe Hairat Suboot Zaki Mehvash 《Monatshefte für Chemie / Chemical Monthly》2020,151(4):599-603
Monatshefte für Chemie - Chemical Monthly - A transition metal-free and efficient TBHP/TBAI-mediated protocol has been developed for the synthesis of 4H-chromen-4-ones from chroman-4-ones via... 相似文献
46.
1‐Morpholin‐4‐yl‐5,6,7,8‐tetrahydroisoquinoline‐4‐carbonitrile ( 2 ) was synthesized from 3‐amino‐1‐thioxo‐5,6,7,8‐tetrahydro‐1H‐isothiochromene‐4‐carbonitrile ( 1 ) and used as starting material to synthesize many thienotetrahydroisoquinolines ( 4 ), which in turn were used in the synthesis of many pyrimidothienotetrahydroisoquinolines. 相似文献
47.
The gas-phase interactions of 2,7-dimethyl-[1,2,4]-triazepine and its thio derivatives with Cu+ were studied through the use of high-level density functional theory (DFT) calculations. The structure of all possible tautomers and their conformers was optimized at the B3LYP/6-31G(d) level of theory. Final energies were obtained at the B3LYP/6-311+G(2df,2p) level. It has been found that the direct association of Cu+ occurs at the oxygen atom attached to position 3 in the case of the dioxo derivative and at the sulfur atom in all other cases. For the dithio derivatives, the global minimum of the PES corresponds to the structure in which the metal ion bridges between the heteroatom at position 3 and the nitrogen atom at position 4 of the corresponding enolic tautomer, forming a four-membered ring structure; for the dioxo derivative, this conformer competes with the ketone tautomer. Moreover, the isomerization processes leading from the most stable adduct to the other stable conformers were investigated. Among all the considered compounds, the 3,5-dithiotriazepines-Cu+ is found to be the one that associates Cu+ more tightly in the gas phase. The calculated Cu+ binding energies show a good correlation with the experimental proton affinities. 相似文献
48.
Hamdoon A. Mohammed Hussein M. Eldeeb Riaz A. Khan Mohsen S. Al-Omar Salman A. A. Mohammed Mohammed S. M. Sajid Mohamed S. A. Aly Adel M. Ahmad Ahmed A. H. Abdellatif Safaa Yehia Eid Mahmoud Zaki El-Readi 《Molecules (Basel, Switzerland)》2021,26(19)
Sage, Salvia officinalis L., is used worldwide as an aromatic herb for culinary purposes as well as a traditional medicinal agent for various ailments. Current investigations exhibited the effects of extended dryings of the herb on the yields, composition, oil quality, and hepatoprotective as well as anti-cancer biological activities of the hydrodistillation-obtained essential oils from the aerial parts of the plant. The essential oils’ yields, compositions, and biological activities levels of the fresh and differently timed and room-temperature dried herbs differed significantly. The lowest yields of the essential oil were obtained from the fresh herbs (FH, 631 mg, 0.16%), while the highest yield was obtained from the two-week dried herbs (2WDH, 1102 mg, 0.28%). A notable decrease in monoterpenes, with increment in the sesquiterpene constituents, was observed for the FH-based essential oil as compared to all the other batches of the essential oils obtained from the different-timed dried herbs. Additionally, characteristic chemotypic constituents of sage, i.e., α-pinene, camphene, β-pinene, myrcene, 1, 8-cineole, α-thujone, and camphor, were present in significantly higher proportions in all the dried herbs’ essential oils as compared to the FH-based essential oil. The in vivo hepatoprotective activity demonstrated significant reductions in the levels of AST, ALT, and ALP, as well as a significant increase in the total protein (p < 0.05) contents level, as compared to the acetaminophen (AAP) administered experimental group of rats. A significant reduction (p < 0.05) in the ALT level was demonstrated by the 4WDH-based essential oil in comparison to the FH-based essential oil. The levels of creatinine, cholesterol, and triglycerides were reduced (p < 0.05) in the pre-treated rats by the essential oil batches, with non-significant differences found among them as a result of the herbs dryings based oils. A notable increase in the viability of the cells, and total antioxidant capacity (TAOxC) levels, together with the reduction in malondialdehyde (MDA) levels were observed by the essential oils obtained from all the batches as compared with the AAP-treated cell-lines, HepG-2, HeLa, and MCF-7, that indicated the in vitro hepatoprotective effects of the sage essential oils. However, significant improvements in the in vivo and in vitro hepatoprotective activities with the 4WDH-based oil, as compared to all other essential oil-batches and silymarin standard demonstrated the beneficial effects of the drying protocol for the herb for its medicinal purposes. 相似文献
49.
Some physical properties (such as lattice parameter, density and porosity) and magnetic properties of the system Mg1‐xZnxFe2O4; where x=0,0.1,0.2,0.3,0.4,0.5and 0.6 have been studied. It was found that the lattice parameter increases with increasing the zinc concentration. The composition dependence of the physical properties is divided into two regions. The first one is for x ≤ 0.3 and the second one is for x > 0.3. From the magnetization measurements, the basic composition (MgFe2O4) shows the lowest magnetization, while the composition of x=0.4 shows the highest one. The behaviour of magnetization M versus composition shows also two regions for x <>0.3. The behaviour of M versus x was discussed in the bases of cation distribution. From the B‐H loops, the remanence induction Br, saturation induction Bs and the coercive force Hc were determined and studied with x. The Curie temperature TC was determined from the measurements of the initial permeability μi versus temperature. It was found TC decreases with increasing Zn‐content. Also paramagnetic temperature TP was determined from the behaviour of MS vs. T. In general it was found TP > TC by about 7‐10 K. 相似文献
50.
In this work, we report the chemical polymerization of pyrrole to obtain thin film of polypyrrole (PPy) hydrochloride deposited onto the electrode of the quartz crystal microbalance (QCM). The film in the base form was exposed to a solution of AgNO3. Electroless reduction for silver ions by the PPy film took place and silver particles were adsorbed onto the film surface. The silver particles content at the PPy films were analyzed by QCM and the results showed that the concentrations of silver uptakes increase as the original AgNO3 solution increases. The morphology of the surface of the PPy film and the silver-PPy film composite were studied by the scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). They showed that the obtained silver particles have spherical, cubic and tetrahedral structures. X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR) were used to characterize the structure of the powder composite. This work reveals the capability of PPy film coating on QCM in sensing and removing silver from several environmental samples. 相似文献