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91.
Mai H. El-Naggar Abdelaziz Elgaml Fatma M. Abdel Bar 《Natural product research》2019,33(11):1556-1562
Ricinine (1), a known major alkaloid in Ricinus communis plant, was used as a starting compound for the synthesis of six ricinine derivatives; two new and four known compounds. The new derivatives; 3-amino-5-methyl-1H-pyrazolo[4,3-c]pyridin-4(5H)-one (2), and 3-amino-5-methyl-1-(phenylsulfonyl)-1H-pyrazolo[4,3-c]pyridin-4(5H)-one (3), as well as the previously prepared derivatives (4–7) were subjected for antimicrobial and antiquorum-sensing evaluation in comparison to different R. communis extracts. Acetyl ricininic acid derivative (5) showed the highest antimicrobial activity among all tested derivatives against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeuroginosa and Candida albicans. However, compound 7 (4-methoxy-1-methyl-2-oxo-1,2-dihydropyridine-3-carboxamide) showed the highest antiquorum-sensing activity among all tested compounds and extracts. These findings proved the usefulness of ricinine as a good scaffold for the synthesis of new antimicrobial and antiquorum-sensing derivatives in spite of its poor contribution to the antimicrobial activity of the plant extracts. 相似文献
92.
Cross-linked polyvinyl alcohol/polyvinyl pyrrolidone/zeolite fibers were prepared in the presence of potassium peroxodisulphate (K2S2O8) under the curing process by the electrospinning technique. The narrowest nanofibers of PVA/PVP (50:50) were prepared under optimum experimental conditions of 2.5 × 10?4 mol of K2S2O8, an applied voltage of 22 KV, the distance of 15 cm and the feed rate of 0.2 mL/h. The progress of the cross-linking was examined by immersion of the prepared nanofibers in water and following the swelling degrees. By raising the K2S2O8 amount and curing time, the cross-linking density was increased. X-ray diffraction (XRD) demonstrated that the crystallinity of the nanofibers was decreased by the increase of K2S2O8 and the lowest crystallinity was observed for PVA/PVP (70:30). The contact angle of nanofibers was decreased from 72° to 34 by increasing PVP ratio from 30 to 70. The morphology of the nanofibers before and after immersion in the simulated body fluid (SBF) was studied using electron scanning microscopy (SEM) and PVA/PVP (70:30) showed the highest changes in the morphology while the lowest one was observed for PVA/PVP (50:50). Moreover, the cross-linked PVA/ PVP with the ratio of 50:50 had the narrowest diameter of 200 ± 100 nm, and by addition of about 0.5% zeolite, it was even reduced more to 150 ± 50 nm. The cross-linked nanofibers (50:50) with 0.5 wt% and 1.5 wt% zeolite nanoparticles showed the tensile modules of 416.26 and 703.52 MPa, respectively, while in the absence of zeolite, it was209.25 MPa. Fibroblast L929 cells were cultured on the cross-linked PVA/PVP/zeolite (50:50:0.5) nanofiber, and the cell proliferation and growth was evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Fibroblasts grew on the surface of scaffold showed good morphology and proliferation after seven days and the absorption amount was increased from 0.075 to 0.78 相似文献
93.
Abdelaziz Ayman A. Ishijima Tatsuo Osawa Naoki Seto Takafumi 《Plasma Chemistry and Plasma Processing》2019,39(1):165-185
Plasma Chemistry and Plasma Processing - This study presented a quantitative evaluation of the performance of a low power miniaturized SDBD source for the production of ozone and nitrogen oxides as... 相似文献
94.
Energy levels, transition probabilities and effective collision strengths for the 1s2 2s2 2p6 3s2 3p6 3d10, and the 1s2 2s2 2p6 3s2 3p6 3d9 4l (l=s, p, d, and f) states of nickel-like Eu are used in the determination of the reduced population for 55 fine structure levels over a wide range of electron densities (from 10+20 to 4×10+22 cm−3) and at various electron plasma temperatures.The gain coefficients for those transitions with positive population inversion factor are determined and plotted against the electron density. 相似文献
95.
M. Mahmoudi S. M. Mousavi M. Sahrai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(2):241-246
We analyze the behavior of optical bistability in a four-level mercury atomic system driven by a cavity and two external coherent
fields by means of a unidirectional ring cavity. We find that without interacting dark resonances and for large intensity
of coupling field, the optical bistability disappears. So, the double dark resonances could significantly establish the optical
bistability. Moreover, we demonstrate that the double dark resonances can dramatically reduce the threshold of optical bistability. 相似文献
96.
Because of their multifunctionality and unique magnetic properties, superparamagnetic iron oxide nanoparticles (SPIONs) have been recognized as very promising materials for various biomedical applications. The main difficulty with the use of SPIONs as multimodal bioimaging agents is their lack of fluorescence. Since cells can act as extremely efficient filters for the elution of surface-bound fluorescent tags with nanoparticles, the surface loaded fluorescence dyes significantly decay after a short period of time. Here, for the first time, we introduce novel, engineered multimodal SPIONs with a permanent fluorescence capability, the study of which can lead to a deeper understanding of biological processes at the biomolecular level, greatly influencing molecular diagnostics, imaging and therapeutic applications. 相似文献
97.
Bringas E Köysüren Ö Quach DV Mahmoudi M Aznar E Roehling JD Marcos MD Martínez-Máñez R Stroeve P 《Chemical communications (Cambridge, England)》2012,48(45):5647-5649
We report here the on-command cargo controlled delivery using an alternating magnetic field (AMF) from magnetic silica mesoporous supports capped with a lipid bilayer. 相似文献
98.
Wessameldin S. Abdelaziz 《Journal of Russian Laser Research》2012,33(1):14-19
We use the energy levels, transition probabilities, and effective collision strengths for the states 1s2 2s2 2p6 3s2 3p6 3d10 and 1s2 2s2 2p6 3s2 3p6 3d9 4 l (l = s, p, d, and f) of a nickel-like Nd ion to determine reduced population for 55 fine-structure levels over a wide
range of electron density values (from 1020 to 4 · 1022 cm
−3) at various electron plasma temperatures in the range of 1–2 keV. We find the gain coefficients for those transitions with
the positive population inversion factor and show their dependences on the electron density. 相似文献
99.
Hayet Benzarouk Abdelaziz Drici Mounira Mekhnache Abdelaziz Amara Mouhamed Guerioune Jean Christian Bernède Hacen Bendjffal 《Superlattices and Microstructures》2012
In the present work we studied the influence of the dopant elements and concentration on the microstructural and electrochemical properties of ZnO thin films deposited by spray pyrolysis. Transparent conductive thin films of zinc oxide (ZnO) were prepared by the spray pyrolysis process using an aqueous solution of zinc acetate dehydrate [Zn(CH3COO)2·2H2O] on soda glass substrate heated at 400 ± 5 °C. AlCl3, MgCl2 and NiCl2 were used as dopant. The effect of doping percentage (2–4%) has been investigated. Afterwards the samples were thermally annealed in an ambient air during one hour at 500 °C. X-ray diffraction showed that films have a wurtzite structure with a preferential orientation along the (0 0 2) direction for doped ZnO. The lattice parameters a and c are estimated to be 3.24 and 5.20 ?, respectively. Transmission allowed to estimate the band gaps of ZnO layers. The electrochemical studies revealed that the corrosion resistance of the films depended on the concentration of dopants. 相似文献
100.
Oxidation by sodium perborate of selected alcohols and unsaturated compounds to ketones and acids was achieved at 60–80°C in the presence of catalytic amounts of chromium(VI) oxide and methyltridecylammonium chloride. 相似文献