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91.
Two simple, sensitive and specific fluorimetric methods have been developed for the determination of some sulphur containing
compounds namely, Acetylcysteine (Ac), Carbocisteine (Cc) and Thioctic acid (Th) using terbium Tb+3 and uranium U+3 ions as fluorescent probes. The proposed methods involve the formation of a ternary complex with Tb+3 in presence of Tris-buffer method (I) and a binary complex with aqueous uranyl acetate solution method (II). The fluorescence
quenching of Tb+3 at 510, 488 and 540 nm (λex 250, 241 and 268 nm) and of uranyl acetate at 512 nm (λex 240 nm) due to the complex formation was quantitatively measured for Ac, Cc and Th, respectively. The reaction conditions
and the fluorescence spectral properties of the complexes have been investigated. Under the described conditions, the proposed
methods were applicable over the concentration range (0.2–2.5 μg ml−1), (1–4 μg ml−1) and (0.5–3.5 μg ml−1) with mean percentage recoveries 99.74±0.36, 99.70±0.52 and 99.43±0.23 for method (I) and (0.5–6 μg ml−1), (0.5–5 μg ml−1), and (1–6 μg ml−1) with mean percentage recoveries 99.38±0.20, 99.82±0.28 and 99.93±0.32 for method (II), for the three cited drugs, respectively.
The proposed methods were successfully applied for the determination of the studied compounds in bulk powders and in pharmaceutical
formulations, as well as in presence of their related substances. The results obtained were found to be in agree statistically
with those obtained by official and reported ones. The two methods were validated according to USP guidelines and also assessed
by applying the standard addition technique. 相似文献
92.
New quininium (Qn) plastic membrane electrodes of the conventional type were constructed and characterized. They are based on incorporation of Qn-reineckate (QnRn) ion-pair, Qn-phosphotungstate (Qn3-PT), or Qn-phosphomolybdate (Qn3PM) ion associate into a poly(vinyl chloride) membrane. The electrodes are selective for Qn and have been successfully used for the determination of Qn2SO4 in pharmaceutical tablets. Nevertheless, they showed, as almost all other ion-selective electrodes, limited life times. Energy dispersive- (EDS) and X-ray photoelectron spectroscopy (XPS), as well as electron microscopy were applied to investigate the cause of this limitation in the life times of the electrodes. The results indicated that the electrodes lose their activity after prolonged soaking as a result of leaching of the ion exchanger from the membranes into the test solution in addition to deformation at the surface of the expired electrode. 相似文献
93.
Alaa S. Abd-El-Aziz Maysun R. Benaaisha Mohammed S. M. Abdelbaky David Martinez-Blanco Santiago García-Granda Amani A. Abdelghani Laila H. Abdel-Rahman Rabin Bissessur 《Molecules (Basel, Switzerland)》2021,26(21)
The development of synthesis methods to access advanced materials, such as magnetic materials that combine multimetallic phosphide phases, remains a worthy research challenge. The most widely used strategies for the synthesis of magnetic transition metal phosphides (TMPs) are organometallic approaches. In this study, Fe-containing homometallic dendrimers and Fe/Co-containing heterometallic dendrimers were used to synthesize magnetic materials containing multimetallic phosphide phases. The crystalline nature of the nearly aggregated particles was indicated for both designed magnetic samples. In contrast to heterometallic samples, homometallic samples showed dendritic effects on their magnetic properties. Specifically, saturation magnetization (Ms) and coercivity (Hc) decrease as dendritic generation increases. Incorporating cobalt into the homometallic dendrimers to prepare the heterometallic dendrimers markedly increases the magnetic properties of the magnetic materials from 60 to 75 emu/g. Ferromagnetism in homometallic and heterometallic particles shows different responses to temperature changes. For example, heterometallic samples were less sensitive to temperature changes due to the presence of Co2P in contrast to the homometallic ones, which show an abrupt change in their slopes at a temperature close to 209 K, which appears to be related to the Fe2P ratios. This study presents dendrimers as a new type of precursor for the assembly of magnetic materials containing a mixture of iron- and cobalt-phosphides phases with tunable magnetism, and provides an opportunity to understand magnetism in such materials. 相似文献
94.
The paper presents a cantilevered composite wing, aeroelastic characteristics of idealized as a composite flat plate laminate. The composite laminate was made from woven glass fibers with epoxy matrix. The elastic and dynamic properties of the laminate were determined experimentally for aeroelastic calculations. Aeroelastic wind tunnel testing of the laminate was performed and the result showed that flutter, a dynamic instability occurred. The cantilevered laminate also displayed limit cycle amplitude, post-flutter oscillation. The experimental flutter velocity and frequency were verified by our computational analysis. 相似文献
95.
Badriah Saad Al-Farhan Maram T. Basha Laila H. Abdel Rahman Ahmed M. M. El-Saghier Doaa Abou El-Ezz Adel A. Marzouk Mohamed R. Shehata Ehab M. Abdalla 《Molecules (Basel, Switzerland)》2021,26(16)
Despite the common use of salens and hydroxyquinolines as therapeutic and bioactive agents, their metal complexes are still under development. Here, we report the synthesis of novel mixed-ligand metal complexes (MSQ) comprising salen (S), derived from (2,2′-{1,2-ethanediylbis[nitrilo(E) methylylidene]}diphenol, and 8-hydroxyquinoline (Q) with Co(II), Ni(II), Cd(II), Al(III), and La(III). The structures and properties of these MSQ metal complexes were investigated using molar conductivity, melting point, FTIR, 1H NMR, 13C NMR, UV–VIS, mass spectra, and thermal analysis. Quantum calculation, analytical, and experimental measurements seem to suggest the proposed structure of the compounds and its uncommon monobasic tridentate binding mode of salen via phenolic oxygen, azomethine group, and the NH group. The general molecular formula of MSQ metal complexes is [M(S)(Q)(H2O)] for M (II) = Co, Ni, and Cd or [M(S)(Q)(Cl)] and [M(S)(Q)(H2O)]Cl for M(III) = La and Al, respectively. Importantly, all prepared metal complexes were evaluated for their antimicrobial and anticancer activities. The metal complexes exhibited high cytotoxic potency against human breast cancer (MDA-MB231) and liver cancer (Hep-G2) cell lines. Among all MSQ metal complexes, CoSQ and LaSQ produced IC50 values (1.49 and 1.95 µM, respectively) that were comparable to that of cisplatin (1.55 µM) against Hep-G2 cells, whereas CdSQ and LaSQ had best potency against MDA-MB231 with IC50 values of 1.95 and 1.43 µM, respectively. Furthermore, the metal complexes exhibited significant antimicrobial activities against a wide spectrum of both Gram-positive and -negative bacterial and fungal strains. The antibacterial and antifungal efficacies for the MSQ metal complexes, the free S and Q ligands, and the standard drugs gentamycin and ketoconazole decreased in the order AlSQ > LaSQ > CdSQ > gentamycin > NiSQ > CoSQ > Q > S for antibacterial activity, and for antifungal activity followed the trend of LaSQ > AlSQ > CdSQ > ketoconazole > NiSQ > CoSQ > Q > S. Molecular docking studies were performed to investigate the binding of the synthesized compounds with breast cancer oxidoreductase (PDB ID: 3HB5). According to the data obtained, the most probable coordination geometry is octahedral for all the metal complexes. The molecular and electronic structures of the metal complexes were optimized theoretically, and their quantum chemical parameters were calculated. PXRD results for the Cd(II) and La(III) metal complexes indicated that they were crystalline in nature. 相似文献
96.
Laila Girgis 《Applied mathematics and computation》2010,216(7):2226-7047
This paper studies the soliton perturbation that are described by three nonlinear wave equations. The adiabatic dynamics of the soliton parameters and the soliton velocity is obtained, in the presence of perturbation terms. The fixed point is also determined in a couple of cases. 相似文献
97.
Five simple and sensitive methods were developed for the determination of leflunomide (I) in the presence of its degradates 4-trifluoromethyl aniline (II) and 3-methyl-4-carboxy isoxazole (III). Method A was based on differential derivative spectrophotometry by measuring the delta(1)D value at 279.5 nm. Beer's law was obeyed in the concentration range of 2.00-20.00 microg/mL with mean percentage accuracy of 100.07 +/- 1.32. Method B depended on first-derivative spectrophotometry and measuring the amplitude at 253.4 nm. Beer's law was obeyed in the concentration range of 2.00-16.00 microg/mL with mean percentage accuracy of 98.42 +/- 1.61. Method C was based on the reaction of degradate (II) with 2,6-dichloroquinone-4-chloroimide (Gibbs reagent). The colored product was measured at 469 nm. Method D depended on the reaction of degradate (II) with para-dimethyl aminocinnamaldehyde (p-DAC). The absorbance of the colored product was measured at 533.4 nm. Method E utilized 3-methyl-2-benzothiazolinone hydrazone in the presence of cerric ammonium sulfate with degradate (II). The green colored product was measured at 605.5 nm. The linearity range was 40.00-280.00, 2.40-24.00, and 30-250 microg/mL with mean percentage accuracy of 100.75 +/- 1.21, 100.13 +/- 1.45, and 99.74 +/- 1.39 for Methods C-E, respectively. All variables were studied to optimize the reaction conditions. The proposed methods have been successfully applied to the analysis of leflunomide in pharmaceutical dosage forms and the results were statistically compared with that previously reported. 相似文献
98.
Cássia G. Magalhães Grácia D. de Fátima Silva Lucienir P. Duarte Isabel L. Bazzocchi Antonio J. Diaz Laila Moujir Manuel R. López Rute C. Figueiredo Sidney A. Vieira Filho 《Helvetica chimica acta》2013,96(6):1046-1054
In continuation of our work on Maytenus salicifolia, we report herein the isolation and structural elucidation of two new compounds, salicassin ( 1 ), a diterpene‐chalcone adduct with an unprecedented C‐framework, and (16β)‐16‐hydroxypristimerin ( 2 ), a quinone methide triterpenoid. Their structures were elucidated on the basis of spectroscopic analysis, including 1D‐ and 2D‐NMR techniques (COSY, ROESY, HSQC, and HMBC). In addition, 22 known compounds were isolated and characterized by comparison of their spectra with reported data. Compound 2 , structurally related to the well known cytotoxic quinone methide triterpenoids, exhibited an antiproliferative effect on HeLa, A‐549, and HL‐60 human cell lines, with IC50 values of 2.2, 3.2, and 2.7 μM , respectively. 相似文献
99.
Laila Jaber-Ansari Myung Gwan Hahm Tae Hoon Kim Sivasubramanian Somu Ahmed Busnaina Yung Joon Jung 《Applied Physics A: Materials Science & Processing》2009,96(2):373-377
Large-scale room-temperature liquid-phase directed assembly of highly organized single-walled carbon nanotubes (SWNT) over
large areas is demonstrated. The presented process utilizes lithographically patterned template to guide the fluidic self-assembly
of SWNTs on a silicon-dioxide substrate. The width of these highly organized SWNT structures are in the micron range while
their heights are in orders of nanometers. Room temperature electrical I–V characterization of these fabricated high coverage SWNT wires show linear ohmic behavior. The resistivity of these assembled
SWNT network is in the order of 10−6 Ω m demonstrating their metallic characteristics during conductance. Scaling of the assembly processes on a wafer level with
high yield is demonstrated. Our developed assembly process is compatible with complimentary metal oxide semiconductor (CMOS)
processes and provides a simple and flexible way of building SWNT nanotube-based electronics in a large scale. 相似文献
100.
Laila Assas Brian Dennis Saber Elaydi George Livadiotis 《Journal of Difference Equations and Applications》2016,22(2):164-176
We consider a single-species stochastic modified Beverton–Holt model with Allee effects caused by predator saturation. We prove that, under some conditions on the parameters, there exists a Markov operator that is asymptotically stable. A stochastic version of the Cushing–Henson conjecture on attenuance and resonance is investigated. 相似文献