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131.
The radiolysis of ethylenediaminetetraacetatocobalt (II) and (III) has been studied, both in the presence and absence of oxygen,
Radiolytic degradation of the metal chelate was observed. Based on the experimental data, a radiolytic degradation mechanism
of the chelates is proposed and discussed. 相似文献
132.
133.
Aly M. Hafez Quoc Trung Hua Mohamed Shaker S. Adam 《Surface and interface analysis : SIA》2021,53(1):21-30
The dimerization of alkanethiol mixtures (hexanethiol, octanethiol, and dodecanethiol) to form self‐assembled monolayers (SAMs) from headspace on nanoporous gold surfaces was studied for the first time using gas chromatography (GC/MS) and time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS). The nanoporous gold surfaces were obtained by an acidic etching of a 585‐gold alloy. Field emission scanning electron microscopy (FE‐SEM) was utilized to study the change of the surface geometry and porosity of the gold surfaces before and after etching. Alkanethiols were deposited from the vapor phase above the thiol solutions (headspace) on nanoporous gold plates and nanoporous gold solid‐phase vmicroextraction (SPME) fibers. The nanoporous gold substrates were analyzed by TOF‐SIMS and GC/MS, respectively. The TOF‐SIMS spectra exhibited various gold–sulfur ion clusters and specific peaks related to the adsorption of thiols such as deprotonated monomers, thiolate–Au, dimers (e.g., dialkyl sulfides–Au and dialkyl disulfides–Au). The GC/MS analysis of headspace extractions of alkanethiol mixtures by nanoporous gold SPME fibers showed a high extraction efficiency of alkanethiol, dialkyl sulfide, and dialkyl disulfide when compared with the commercial SPME fibers (DVB‐CAR‐PDMS and CAR‐PDMS). Different GC/MS optimization factors were studied including the extraction time and desorption temperature. 相似文献
134.
Mohamed Faisal Lutfi Abdel-Moneim Hafez Abdel-Moneim Ashwag Saleh Alsharidah Mugahid A. Mobark Ahmed A. H. Abdellatif Imran Y. Saleem Osamah Al Rugaie Khalid M. Mohany Mansour Alsharidah 《Molecules (Basel, Switzerland)》2021,26(8)
The aim of the present study was to assess the short-term effects of Thymoquinone (TQ) on oxidative stress, glycaemic control, and renal functions in diabetic rats. DM was induced in groups II and III with a single dose of streptozotocin (STZ), while group I received no medication (control). The rats in groups I and II were then given distilled water, while the rats in group III were given TQ at a dose of 50 mg/kg body weight/day for 4 weeks. Lipid peroxidase, nitric oxide (NO), total antioxidant capacity (TAC), glycated haemoglobin (HbA1c), lipid profiles, and renal function were assessed. Moreover, the renal tissues were used for histopathological examination. STZ increased the levels of HbA1c, lipid peroxidase, NO, and creatinine in STZ-induced diabetic rats in comparison to control rats. TAC was lower in STZ-induced diabetic rats than in the control group. Furthermore, rats treated with TQ exhibited significantly lower levels of HbA1c, lipid peroxidase, and NO than did untreated diabetic rats. TAC was higher in diabetic rats treated with TQ than in untreated diabetic rats. The histopathological results showed that treatment with TQ greatly attenuated the effect of STZ-induced diabetic nephropathy. TQ effectively adjusts glycaemic control and reduces oxidative stress in STZ-induced diabetic rats without significant damaging effects on the renal function. 相似文献
135.
Madiha A. Shoeib Medhat M. Kamel Salah M. Rashwan Omar M. Hafez 《Surface and interface analysis : SIA》2015,47(6):672-680
Composite Ni–P/nano‐TiO2 coatings were prepared by simultaneous electroless deposition of Ni–P and nano‐TiO2 on a low carbon steel substrate. The deposition was carried out from stirred solutions containing suspended nano‐TiO2 particles. The Ni–P and Ni–P/nano‐TiO2 coatings before and after heat treatment were characterized by X‐ray diffraction, scanning electron microscopy and energy dispersive X‐ray spectroscopy. The micro‐structural morphologies of the coatings significantly varied with the nano‐TiO2 content. The corrosion resistance of as‐plated and heat‐treated Ni–P and Ni–P/nano‐TiO2 coatings was investigated by anodic polarization, Tafel plots and electrochemical impedance spectroscopic (EIS) studies in 3.5% NaCl solution. Ni–P/nano‐TiO2 coating exhibited superior corrosion resistance over Ni–P coating. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
136.
The application of He's variational iteration method to nonlinear equations arising in heat transfer
In this Letter, we purpose to solve nonlinear equations arising in heat transfer through the He's variational iteration method (VIM) and show that it is strongly and simply capable of solving a large class of linear or nonlinear differential equations without the tangible restriction of sensitivity to the degree of the nonlinear term and also is very user friend because it reduces the size of calculations besides, its iterations are direct and straightforward. VIM can apply to the nonlinear equations with boundary or initial conditions defined in different points just with developing the correction functional using the extra parameters such as cn, as used in this Letter. 相似文献
137.
138.
Nickel di-silicide formation induced by RTA process at 850 °C for 60 s in the Ni/Si(1 0 0) systems are investigated as a function of the initial Ni film thickness of 7-89 nm using XRD, RBS, SEM, X-SEM and AFM. Based on the XRD and RBS data, in the silicide films of 400-105 nm, NiSi and NiSi2 silicide phases co-exist, indicating that Ni overlayer is completely transformed to NiSi and NiSi2 silicide phases. SEM reveals that these films consist of large grains for co-existence of NiSi2 and NiSi phases, separated from one another by holes, reflecting that NiSi2 grows as islands in NiSi matrix. These films have low sheet resistance, ranging from 1.89 to 5.44 Ω/□ and good thermal stability. For thicknesses ≤ 80 nm RBS yields more Si-rich silicide phases compared to thicker films, whereas SEM reveals that Si-enriched silicide islands with visible holes grow in Si matrix. As the film thickness decreases from 400 to 35 nm, AFM reveals a ridge-like structure showing a general trend of decreasing average diameter and mean roughness values, while sheet resistance measurements exhibit a dramatic increase ranging from 1.89 to 53.73 Ω/□. This dramatic sheet resistance increase is generated by substantial grain boundary grooving, followed by island formation, resulting in a significant phase transformation from NiSi2-rich to Si-rich silicide phases. 相似文献
139.
E.H. Doha A.H. Bhrawy R.M. Hafez 《Communications in Nonlinear Science & Numerical Simulation》2012,17(10):3802-3810
This paper reports a spectral tau method for numerically solving multi-point boundary value problems (BVPs) of linear high-order ordinary differential equations. The construction of the shifted Jacobi tau approximation is based on conventional differentiation. This use of differentiation allows the imposition of the governing equation at the whole set of grid points and the straight forward implementation of multiple boundary conditions. Extension of the tau method for high-order multi-point BVPs with variable coefficients is treated using the shifted Jacobi Gauss–Lobatto quadrature. Shifted Jacobi collocation method is developed for solving nonlinear high-order multi-point BVPs. The performance of the proposed methods is investigated by considering several examples. Accurate results and high convergence rates are achieved. 相似文献
140.
S. Iglesias-Groth Y. Hafez G. Angelini F. Cataldo 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1073-1083
The γ radiolysis of fullerene C60 dispersed in H2O, H2O/NH3, H2O/methanol and H2O/NH3/methanol was studied at 250 and 500 kGy. It was found that C60 originally insoluble in the above mentioned hosting matrix became soluble as a consequence of multiple hydroxylation and oxidation reaction produced by the free radicals generated by the radiolysis of the hosting matrix. The changes undergone by C60 were studied by infrared spectroscopy (FT-IR) and by electronic absorption spectroscopy. The astrochemical consequences of the present study are that C60 ejected in the interstellar medium for instance from protoplanetary and planetary nebulae can condense together with water and other ices in dense molecular clouds. Under the action of high energy radiation C60 reacts with the free radicals generated from the matrix where it is embedded it is solubilized and consequently its carbon content becomes available for further abiotic processes of synthesis of molecules of astrobiological interest. The behavior of C60 appears comparable to that of common PAHs which are also hydroxylated and oxidized under similar conditions. 相似文献